Titanium alloy powder gas atomization fluid field cooperative control method for additive manufacturing

Abstract

The invention relates to the technical field of induction melting load energy cooperative control, and discloses a titanium alloy powder gas atomization fluid field cooperative control method for additive manufacturing, which comprises the following steps: establishing an induction melting load and nozzle interference reference to determine an atomization area coordinate; geometric parameters of the gas supply system are set to generate a negative pressure gradient area; load power drift data are collected, the melt pulsating quantity is determined through a mapping function, the impedance of a gas supply loop is adjusted so as to finely adjust gas phase kinetic energy, and the axial suction pressure is used for carrying out falling fluctuation on the melt; the gas phase kinetic energy is synchronously adjusted according to the real-time power, the energy density of the atomization area is kept stable, and localization control over the crushing area is achieved. The spontaneous damping characteristic of the negative pressure gradient area is used for counteracting melt flow rate pulsation, it is ensured that the energy density is locked in the crushing critical interval, and dynamic coupling stability of the gas phase kinetic energy and the melt flow is achieved; and the fine powder output rate is effectively increased, and the reverse spraying risk is avoided.

Description

Technical Field

[0001] This invention relates to a method for coordinated control of the gas atomization fluid field of titanium alloy powder for additive manufacturing, belonging to the field of coordinated control of load energy in induction melting. Background Technology

[0002] Currently, electrode induction melting gas atomization systems have become a core component in the preparation of high-performance metal powders. These systems use a high-frequency power supply to drive an induction coil, melting the end of a rotating electrode to generate a falling liquid metal jet. The jet is then broken up by a supersonic gas flow from a tightly coupled atomizing nozzle. However, the electrical load during induction melting often exhibits dynamic evolution, causing the melt flow rate to pulsate with fluctuations in induction power and the thermal field. Existing control methods typically set static process parameters and use fixed atomization pressure and gas flow rate. To cover the instantaneous fluctuations in melt flow rate, the system usually needs to maintain a high gas kinetic energy redundancy. This not only increases argon consumption costs but also poses a risk of backflow.

[0003] While the industry often improves powder quality by optimizing nozzle orientation or modifying crucible materials and hardware, hardware improvements have reached physical limits and cannot fundamentally solve the problem of flow field instability caused by load fluctuations. As a result, the adaptive shortcomings in control methods have become a bottleneck restricting the production of high-quality powders. For example, Chinese invention patent CN103846447B discloses a gas atomization preparation method for micro-spherical titanium or titanium alloy powder, which uses a double-layer nozzle structure to introduce hydrogen gas to forcibly passivate and cool the molten droplets to suppress powder oxidation. Conventional improvement paths often involve increasing atomization pressure or changing nozzle geometry, but analysis shows that increasing pressure often leads to an upward shift of the airflow stagnation point, resulting in the risk of melt adhering to the wall. Adjusting the gap can dilute the energy density of the breakup process, revealing an imbalance in the energy ratio between the power output of induction melting and the dynamic atomization flow field.

[0004] Specifically, existing technologies have the following shortcomings: 1. The control loop lacks a physical damping mechanism for melt flow rate fluctuations; 2. The static energy configuration mode leads to increased gas consumption and the risk of backflow; 3. The flow field stagnation point will undergo vertical displacement with fluctuations in melting power, making it impossible to maintain spatial consistency in the recirculation zone. Therefore, how to construct an adaptive matching mechanism for flow field impedance under the condition of dynamic fluctuations in induced melting load, to achieve spatial locking of the atomization stagnation point and stabilize the crushing environment, has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for coordinated control of the gas atomization fluid field of titanium alloy powder for additive manufacturing, comprising the following steps: Step S101: Establish a spatial interference reference between the induction melting load and the atomizing nozzle. Set the nozzle angle of the atomizer to 35° to 45°. Perform three-dimensional interference positioning on the intersection point of the copper nozzle end and the annular airflow to establish the spatial position of the atomization center area. Step S102: Determine the annular airflow gap of the air supply system and the extension length of the copper nozzle, so that the ratio of the annular airflow gap to the extension length of the copper nozzle meets the preset geometric coupling ratio, and use the Venturi effect generated by the airflow flowing through the annular constraint channel to generate a negative pressure gradient region with pressure compensation characteristics at the end of the copper nozzle. Step S103: Real-time acquisition of power drift data of induction melting load, determination of melt flow rate pulsation through mapping function of power drift data and melt mass flow rate, and adjustment of loop impedance of gas supply system according to pulsation to fine-tune output intensity of gas phase kinetic energy, and use axial suction pressure generated in negative pressure gradient zone to offset melt falling pressure fluctuation caused by pulsation. Step S104: The output intensity of gas phase kinetic energy is synchronously adjusted according to the real-time output power of the induction melting load, so that the energy density of the atomization center area is maintained above the critical value of titanium alloy droplet breakage. The localization control of the titanium alloy droplet breakage area is achieved through the physical constraint of spatial position.

[0006] Preferably, in step S102, the geometric coupling ratio ranges from 5 to 12. The negative pressure gradient region uses the pressure difference within the annular constraint channel to convert the gas phase pressure energy into a suction force for the melt falling process, in order to compensate for the flow field pulsation in the atomization center region caused by the real-time output power fluctuation of the induction melting load.

[0007] Preferably, in step S103, the mapping function obtains the real-time current value of the induction coil and multiplies the real-time current value with the impedance change rate of the induction melting load to generate a discrete sequence characterizing the melt flow rate, and adjusts the opening of the proportional valve of the gas supply system according to the discrete sequence.

[0008] Preferably, when the fluctuation range of the real-time current value exceeds the preset deviation threshold, the output pressure of the gas supply system is increased to keep the Weber number in the atomization center area above the critical threshold for titanium alloy melt breakage, so as to avoid melt backflow.

[0009] Preferably, the geometric coupling ratio is represented by the symbol R, and its calculation formula is as follows: R=L / δ, where L is the extension length of the copper nozzle and δ is the annular airflow gap.

[0010] Preferably, after performing step S104, the process further includes an online particle size adjustment step: obtaining the grading pressure of the cyclone separator, establishing a dynamic correlation model between the grading pressure and the operating frequency of the induced draft fan, and controlling the pressure gradient in the gas atomization chamber by adjusting the operating frequency of the induced draft fan.

[0011] Preferably, in step S101, the magnetic field distribution of the induction melting load is changed by adjusting the inter-turn spacing of the induction coil, thereby controlling the melt superheat fluctuation in the atomization center region to be less than 10°C.

[0012] Preferably, in step S103, the control logic for axial suction pressure further includes: monitoring the electromagnetic impedance signal of the inner wall of the copper nozzle, and increasing the external induced draft power to increase the pressure difference in the negative pressure gradient zone when the phase drift rate of the electromagnetic impedance signal conforms to the wall-mounted characteristic curve.

[0013] Preferably, the output pressure of the gas supply system is set to 3.0 MPa to 6.0 MPa, and the energy continuity of the titanium alloy droplet breakup process is maintained by utilizing the self-stabilizing flow field established by the geometric coupling ratio when the output pressure is 4.0 MPa to 5.0 MPa.

[0014] Preferably, in step S104, by establishing a collaborative logic control spectrum involving the real-time output power of the induction melting load, the output pressure of the gas supply system, and the geometric coupling ratio, the optimal energy utilization node of the atomization center region is locked, so that the yield of powder with a particle size of less than 45μm meets the preset production standard.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the gas atomization fluid of titanium alloy powder, by selecting the geometric coupling ratio between the atomizer ring peak gap and the copper nozzle extension length, a negative pressure gradient feedback field with physical damping characteristics can be constructed at the end of the melt flow channel outlet. It utilizes the Venturi effect generated when the airflow passes through the annular confined space to convert the gas phase dynamic pressure energy into a dynamic suction compensation force for the melt falling process, so as to offset the melt flow rate pulsation caused by electrode morphology evolution or power fluctuation during induction melting. This adaptive hedging logic at the physical level ensures that the energy density of the atomization core area is always locked in the critical range of efficient metal droplet breakage, thereby achieving deep coupling stability between gas phase kinetic energy and liquid phase mass flow rate without the need for additional closed-loop detection devices.

[0016] 2. By adopting a nonlinear matching regulation logic of pressure and flow rate, the energy transfer efficiency during the gas expansion process is optimized. When the power on the induction melting load side drifts, the Weber number of the atomization core area is controlled by fine-tuning the gas supply impedance, so that it can be maintained within the preset crushing range. This changes the traditional process that relies solely on increasing static pressure to improve the crushing effect. Under lower pressure conditions, since the gas flow velocity and the melt jet diameter evolve synchronously, a crushing effect superior to the traditional high-pressure scheme can still be achieved. This reduces the power consumption load of the argon circulation system and avoids the risk of backflow caused by ultra-high pressure jet.

[0017] 3. By establishing spatial interference constraints between the copper nozzle extension length and the intersection point of the annular airflow, the atomization stagnation point is locked within the vertical space below the end of the copper nozzle. This locking mechanism can effectively suppress the random drift of the center position of the reflux zone and prevent high-temperature molten droplets from contacting the inner wall of the atomizer due to flow field instability during the crushing process, thereby eliminating the risk of furnace blockage caused by droplet adhesion. This spatial constraint effect of the physical dimension allows secondary crushing to occur in a thin layer region with uniform energy distribution, thereby producing alloy powder particles with narrower particle size distribution and good sphericity, thus improving the powder yield of additive manufacturing raw material powder. Attached Figure Description

[0018] Figure 1 This is an overall process flow diagram of the gas atomization fluid field coordinated control method of the present invention; Figure 2 This is a control logic block diagram of the dynamic coupling between gas phase kinetic energy and melt load in this invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The following embodiments are intended to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0020] A method for coordinated control of the gas atomization fluid field of titanium alloy powder for additive manufacturing is disclosed. This method achieves precise intervention in the breakup behavior of metal droplets through stages such as establishing a geometric flow field constraint benchmark, establishing dynamic impedance matching logic for pressure and flow rate, and forming a closed-loop lock-up of the flow field stagnation point position. The method employs a coordinated control logic for induction melting load energy, mapping the electrical load fluctuations during induction melting into physical-level fine-tuning of the gas phase kinetic energy, thereby stabilizing the energy density in the atomization center region within the critical range for titanium alloy breakup. In the stage of constructing the geometric flow field constraint benchmark, to address the random pulsations in melt flow rate caused by the non-uniform distribution of the induction melting heat field, the system establishes a spatial interference benchmark between the induction melting load and the atomizing nozzle. Specifically, the nozzle angle of the atomizer is set to 35° to 45°, and the copper nozzle tip is positioned relative to the annular gas... Three-dimensional interference positioning is performed at the flow confluence point to establish the spatial position of the atomization center area. Based on this, according to the preset viscosity of the titanium alloy melt, the annular airflow gap δ of the tightly coupled atomizer is set to 1mm to 3mm, and the geometric coupling ratio R between the extension length L of the copper nozzle and the annular airflow gap δ is set to 5 to 12. The calculation formula is as follows: R=L / δ, where R is the geometric coupling ratio; L is the extension length of the copper nozzle; and δ is the annular airflow gap. The Venturi effect generated by the airflow flowing through the annular constraint channel is used to generate a negative pressure gradient region with pressure compensation characteristics at the end of the copper nozzle. The pressure difference in the annular constraint channel is used to convert the gas phase pressure energy into axial suction pressure for the melt falling process, in order to compensate for the flow field pulsation caused by the real-time output power fluctuation of the induction melting load.

[0021] The physical damping effectiveness under actual working conditions was calibrated using the geometric coupling ratio R. The ratio of the nozzle extension length L and the annular airflow gap δ was selected to evaluate the flow field stability. During the equipment assembly stage, a pressure sensor was used to measure the static pressure at the nozzle tip to calibrate the Venturi effect intensity. The axial position of the nozzle was adjusted within a preset range of 5 to 12. The electromagnetic fluctuation environment of the production process was simulated using noise interference signals. The pressure gradient distribution in the negative pressure gradient region was measured under different output pressures. It was determined that when the geometric coupling ratio R is between 8.0 and 8.5, the axial suction pressure generated by the airflow through the annular constraint channel reaches its peak. Its physical boundary is defined as: within the vertical space 3 mm below the nozzle outlet, through the Pitot tube... The array measured an axial airflow velocity of Mach 1.8, at which point the Venturi effect provides the most ideal damping for the molten material's falling fluctuations, limiting the vertical spatial displacement of the airflow stagnation point to within 0.5 mm. During the actual dynamic process of smelting and powdering, the system uses a pressure mapping-differential correction model to estimate the intensity of the negative pressure gradient zone in real time: a pressure transmitter installed at the nozzle's main air supply pipe collects the total inlet pressure in real time, and combined with the pre-calibrated airflow expansion coefficient under the geometric coupling ratio R, calculates the theoretical static pressure at the end of the copper nozzle; simultaneously, a micro-differential pressure sensor positioned at the top of the atomization chamber captures the ambient pressure inside the chamber in real time, and calculates the theoretical static pressure value. Differential calculations are performed with ambient pressure to calculate the relative negative pressure value in the negative pressure gradient zone in real time. This value is then used as a feedback parameter to correct the pressure compensation operator K in real time, ensuring that the physical damping characteristics are consistent with the real-time pulsation of the melt. The calibration process establishes the geometric boundary conditions of the physical damping mechanism, enabling the system to compensate for flow field pulsations caused by spontaneous pressure differences in the airflow during smelting power fluctuations, limiting the spatial displacement of the airflow stagnation point to within 0.5 mm. During the stage of establishing dynamic impedance matching logic for pressure and flow, to address the imbalance in breakage energy density caused by the dynamic evolution of the induction smelting load, the system collects the power drift data of the induction smelting load in real time. This data is obtained by acquiring the induction coil... The real-time current value is obtained and multiplied with the impedance change rate of the induction melting load to generate a discrete sequence characterizing the melt flow rate. Specifically, the logic for obtaining the impedance change rate is as follows: the control system collects the root mean square value of the voltage feedback and the root mean square value of the current feedback across the induction coil in real time with a sampling period of 10ms, calculates the ratio of the two to obtain the real-time impedance, and takes the real-time impedance value of the current sampling period and subtracts the impedance value of the previous sampling period to obtain the difference. The product operation is as follows: the real-time current value is multiplied by the difference, and then multiplied by a physical conversion coefficient characterizing the efficiency of electromagnetic energy conversion to melt mass flow. In this embodiment, the physical conversion coefficient is preset to 0.85; The physical conversion coefficient is obtained by calibration through a pre-conducted power-melt flow rate mapping experiment based on the electromagnetic coupling efficiency of a specific induction melting system, the thermophysical parameters of titanium alloys, and the heat loss of the melting chamber. The specific calibration process is as follows: Under standard melting conditions, the melt mass flow rate under steady-state induction power is obtained by weighing method. The power fluctuation and flow rate pulsation are linearly regressed using the least squares method, and the slope of the calculated regression equation is used as the physical conversion coefficient of the system. Since the system has about 15% electromagnetic dissipation and heat radiation loss, the value of this coefficient in commonly used titanium alloy gas atomization equipment is usually between 0.82 and 0.88. In this embodiment, the median value of 0.85 is taken to ensure calculation accuracy, thereby linearly mapping the electromagnetic load fluctuation to the mass flow rate pulsation representing the melt in kilograms per minute. The specific mathematical form of the physical conversion coefficient and mapping function is obtained by calibration through offline gradient power melting experiments. The calibration process is as follows: For titanium alloy electrodes of fixed specifications, 5-10 sets of different power levels are executed under standard process conditions. The step melting test utilizes the displacement sensor of the electrode feed mechanism to record the electrode loss rate under steady-state power conditions, which is then converted into melt mass flow rate. Subsequently, the least squares method is used to perform linear regression fitting on the discrete data points of the product of induced current and real-time impedance. The slope of the fitted equation is established as the physical conversion coefficient to ensure the physical authenticity of the conversion from electromagnetic load to mass flow rate. The calibration of the pressure compensation operator K is performed during the system's non-melting preheating stage by sending a pressure disturbance signal with a step amplitude of 0.1 MPa to the gas supply system, simultaneously measuring the vertical displacement response of the airflow stagnation point, and using the second derivative to calculate the optimal gain increment. This aims to balance response speed and adjustment stability. Based on this discrete sequence, the opening of the proportional valve of the gas supply system is adjusted to fine-tune the gas phase kinetic energy output intensity. When the fluctuation amplitude of the real-time current value exceeds the preset deviation threshold, the system increases the output pressure of the gas supply system to maintain the Weber number We in the atomization center region above the critical threshold for titanium alloy melt breakage, thus avoiding the risk of melt backflow. The formula for calculating the Weber number We is as follows: We = ρ. g ·v 2 ·d m / σ, where We is the Weiber number, ρ g Let ρ be the gas density, v be the velocity of the gas flow relative to the melt, and d be the velocity of the gas flow relative to the melt. m σ is the diameter of the melt jet, and σ is the surface tension of the titanium alloy liquid.

[0022] The mapping function between induction melting load power drift data and melt mass flow rate was determined. The product of the real-time current value of the induction coil and the corresponding impedance change rate was selected to characterize the discrete sequence data of melt flow rate. During the non-melting preheating stage of the system, gradient power interference test was performed to calibrate the pressure compensation operator K. The pressure compensation operator K is related to the induction current deviation and the gas supply system opening correction requirements. The specific numerical calibration procedure is as follows: the induction power is controlled to vary in increments of 5kW within the range of 200kW to 300kW. The pressure feedback value of the melt flow channel outlet is recorded at each power node. The pressure compensation operator K is determined by performing linear regression calculation through the current deviation and pressure feedback fluctuation. The essence of this pressure compensation operator K is the conversion gain from electromagnetic energy density to fluid kinetic energy. By establishing a causal chain of current dispersion-pressure compensation-momentum balance at the physical level, the control... The system can convert the discrete deviation of the electrical signal into the displacement increment of the proportional valve actuator, thereby ensuring that the system still has a certain process stability under varying operating conditions. The specific calibration steps are as follows: During the 300s preheating stage before the formal melting of the system, the control induction power is used to perform 20 sets of gradient jump tests in the range of 200kW to 300kW with a step amplitude of 5kW. The pressure feedback fluctuation value of the melt flow channel outlet at each power node is recorded simultaneously. The pressure increment and current deviation rate are linearly fitted using the least squares method, and the slope obtained is the pressure compensation operator. In this embodiment, the calibration value of the operator is 0.18. The control unit synchronously corrects the opening degree S of the proportional valve of the gas supply system according to the real-time current deviation rate, where S is the stroke displacement. The gas phase kinetic energy increment is used to offset the kinetic energy impact formed by the melt flow rate pulsation.

[0023] During the closed-loop locking stage at the flow field stagnation point, to suppress the risk of wall adhesion caused by random drift at the center of the recirculation zone, the system controls the copper nozzle extension length to be within the range of 5mm to 10mm, creating physical spatial interference with the annular airflow intersection point, thus locking the atomization stagnation point within the vertical space below the end of the copper nozzle. This ensures that secondary crushing occurs in a region with uniform energy distribution, thereby obtaining alloy powder with a narrow particle size distribution. The system synchronously adjusts the output intensity of the gas phase kinetic energy according to the real-time output power of the induction melting load. Specifically, the synchronous adjustment is achieved through feedforward compensation logic preset in the control unit: the control system acquires the discrete value of the induction melting output power P in real time with a sampling period of no more than 10ms and inputs it into a preset cooperative logic control spectrum. This spectrum defines the power fluctuation ΔP and the output pressure P of the gas supply system. g The dynamic mapping relationship between them, i.e., P g=f(P,R), when the induced power increases due to changes in electrode morphology, the control system calculates the pressure correction value required to maintain a constant Weber number We within the same sampling period, and drives the proportional valve actuator to change the momentum output of the airflow. Through this instantaneous follow-up of gas phase kinetic energy based on power prediction, the envelope of gas phase kinetic energy coincides with the pulsating phase of melt flow rate in real time, thereby achieving quasi-static synchronization of energy density and mass flow rate at the physical level. By establishing a collaborative logic control spectrum involving real-time output power, gas supply system output pressure, and geometric coupling ratio R, the energy utilization node of the atomization center area is locked, ensuring that the yield of powder with a particle size of less than 45μm meets the preset production standard. To enhance the adaptability of the powder preparation process to interference from uneven thermal field distribution of the induction coil, the system changes the magnetic field distribution by adjusting the inter-turn spacing of the induction coil, controlling the melt superheat fluctuation in the atomization center area to be less than 10℃. At the same time, the control logic of axial suction pressure also includes monitoring the electromagnetic impedance signal of the inner wall of the copper nozzle. When the phase drift rate of the anti-signal conforms to the wall-mounting characteristic curve, the generation mechanism of this wall-mounting characteristic curve lies in using the inner wall of the copper nozzle as the detection interface of the high-frequency electromagnetic induction circuit. When high-temperature titanium alloy droplets adhere, their conductivity and permeability will cause a step jump in the complex impedance modulus of the induction circuit. In specific implementation, by establishing an experimental correlation mapping table between the offset of the phase angle θ and the physical thickness of the adhesion layer, the phase drift rate is used as the physical fingerprint to identify the initial stage of wall-mounting, thereby increasing the external induced draft power to improve the pressure difference in the negative pressure gradient zone. After performing localized control of the titanium alloy droplet breakup area, the staged pressure of the cyclone separator is obtained, and a dynamic correlation model between the staged pressure and the operating frequency of the induced draft fan is established. The pressure gradient in the atomization chamber is controlled by adjusting the operating frequency of the induced draft fan. The output pressure of the air supply system is set to 3.0MPa to 6.0MPa. Using the self-stabilizing flow field established by the geometric coupling ratio R, the energy continuity of the titanium alloy droplet breakup process is maintained when the output pressure is 4.0MPa to 5.0MPa.

[0024] Example 1: In the continuous production of TC4 titanium alloy powder for additive manufacturing using electrode induction gas atomization, the physical reduction in electrode diameter during the melting process causes a nonlinear shift in the mutual inductance impedance of the induction coil. When the system faces the objective condition of frequent fluctuations in induction power between 250kW and 280kW and transient pulses in melt flow rate between 1.5kg / min and 2.2kg / min, the system, according to the method path in the aforementioned specific embodiment, determines the annular gas flow gap δ to be 2.0mm and... The nozzle extension length L is set to 16mm to obtain a geometric coupling ratio R of 8.0. The formula for calculating the geometric coupling ratio R is as follows: R=L / δ, where R is the geometric coupling ratio; L is the extension length of the copper nozzle; and δ is the annular airflow gap. The negative pressure gradient zone generated in the annular constraint channel generates axial suction pressure for the melt jet at the end of the copper nozzle, which is used as a physical damping mechanism to absorb the kinetic energy increment of the melt flow rate. The system synchronously collects the real-time current signal of the induction melting load and converts it into a proportional valve opening adjustment command for the gas supply system.

[0025] Under the flow field stability benchmark established by the geometric coupling ratio R, dynamic impedance compensation is implemented within the atomization pressure range of 4.2MPa to 4.8MPa. Through the synergistic effect of the physical constraint of the negative pressure gradient zone and the active feedback adjustment of the gas phase kinetic energy, the spatial displacement of the airflow stagnation point is controlled within 0.5mm. This solves the technical contradiction between the high gas consumption caused by maintaining high air kinetic energy redundancy to cover flow rate fluctuations and the dilution of breakup energy density. This keeps the Weber number We in the atomization center region continuously within the preset critical range for titanium alloy droplet breakup. Ultimately, the yield of titanium alloy powder with a particle size of less than 45μm is stabilized at over 55%, and there is no backflow dust accumulation in the gas atomization chamber. The physical constraint established by the geometric coupling ratio R and the dynamic feedback logic based on power mapping jointly construct an adaptive flow field energy regulation closed loop. By introducing a pressure compensation mechanism at the breakup source to offset the energy dispersion caused by external load fluctuations, the gas atomization process is controlled by the deterministic engineering procedures of geometric boundaries and electrical feedback.

[0026] Example 2: Experimental verification of the technical effectiveness of the fluid field collaborative control method in handling melt flow rate pulsations caused by nonlinear electromagnetic induction fluctuations during titanium alloy electrode induction melting. An industrial-grade electrode induction melting gas atomization system was used, equipped with an electric power monitoring unit with a measurement accuracy of 0.1kW and a gas pressure regulation circuit with a response frequency of not less than 50Hz. To simulate the electromagnetic interference environment in real industrial production, Gaussian white noise with a signal-to-noise ratio of 15dB was actively superimposed on the power supply circuit of the induction coil, and power frequency interference at a frequency of 50Hz was simulated. Regarding the core technical parameters, geometric coupling... The calibration logic of the coupling ratio R is a technical trade-off between establishing the suction strength of the negative pressure gradient zone and avoiding the risk of melt backflow. When the annular airflow gap δ decreases, the efficiency of converting static pressure energy into kinetic energy in the channel increases. If the extension length L of the copper nozzle is not set sufficiently, a Venturi effect center with physical damping characteristics cannot be generated at the end of the melt flow channel outlet. Under the typical working condition of maintaining the superheat of titanium alloy melt at 150°C, the geometric coupling ratio R is determined to be 8.5 based on the dynamic matching relationship between melt viscosity and gas phase shear force. This value is used as the geometric constraint benchmark for flow field stability.

[0027] The original input data was collected, and the real-time output power of the inductive smelting load exhibited random fluctuations of 12.5kW at an average value of 260kW. In the control group, under conditions lacking dynamic impedance matching logic and with the geometric coupling ratio R set to the conventional value of 3.0, the pressure ripple in the atomization chamber reached 18.2%, and the yield of fine powder with a particle size less than 45μm was 39.5%. In contrast, the sample group of this invention converted the real-time current deviation into the stroke increment of the gas supply proportional valve through a power mapping function. After executing this technical action, key intermediate data was generated. The measured pressure difference in the negative pressure gradient zone at the end of the copper nozzle was dynamically compensated from the initial 0.32MPa to 0.48MPa. This physical compensation mechanism generated axial suction pressure against the melt jet, reducing the vertical axial displacement of the atomization stagnation point from 4.5mm in the control group to 0.38mm. The final yield determination results showed that the fine powder yield was significantly higher. The powder yield remained stable at 57.2%. In the empirical verification of the key parameter boundaries, the geometric coupling ratio R was set to the lower limit of 4.5, which was outside the range. Due to the insufficient spontaneous damping characteristics of the negative pressure gradient region to cover the increase in melt falling pressure caused by the power peak, the droplet breakup environment became unsteady and discrete, and the fine powder yield dropped to 42.6%. When the geometric coupling ratio R was set to the upper limit of 13.0, although the axial suction pressure increased, the excessive geometric ratio caused the center position of the recirculation zone to shift downstream of the nozzle, and the energy utilization rate of the atomization center region entered the saturation zone and showed a downward inflection point. By setting the induced power fluctuation gradient to 10kW, 20kW and 30kW, the gradient verification was carried out. The results showed that the breakup energy density deviation rate of the sample group of the present invention showed a controlled monotonic correlation trend with the interference intensity, which confirmed that the method of the present invention has process stability under variable working conditions.

[0028] Example 3: This example combines Figures 1 to 2 This paper describes a method for the coordinated control of the gas atomization fluid field of titanium alloy powder for additive manufacturing. Figure 1 As shown, step S101 establishes a spatial interference reference between the induction melting load and the atomizing nozzle, sets the nozzle angle of the atomizer to 35° to 45°, and performs three-dimensional interference positioning of the intersection point of the copper nozzle end and the annular airflow to establish the spatial position of the atomization center area. Step S102 determines the annular airflow gap of the air supply system and the extension length of the copper nozzle, so that the ratio of the annular airflow gap to the extension length of the copper nozzle conforms to the preset geometric coupling ratio. Utilizing the Venturi effect generated by the airflow flowing through the annular constraint channel, a negative pressure gradient region with pressure compensation characteristics is generated at the end of the copper nozzle. Step S10... 3. Real-time acquisition of power drift data of induction melting load, determination of melt flow rate pulsation through mapping function, and adjustment of the loop impedance of gas supply system according to pulsation to fine-tune gas phase kinetic energy output intensity. The axial suction pressure generated by the negative pressure gradient zone is used to offset the melt falling pressure fluctuation caused by pulsation. Step S104: Synchronously adjust the output intensity of gas phase kinetic energy according to the real-time output power of induction melting load, so that the energy density of the atomization center area is maintained above the critical value of titanium alloy droplet breakage. Localization control of titanium alloy droplet breakage area is achieved through physical constraints of spatial position.

[0029] like Figure 2 As shown, the control logic system is based on the induction melting load to collect power drift data, and then determines the melt flow rate pulsation. This pulsation data, together with the input from the gas supply system, acts to adjust the gas supply circuit impedance. The system simultaneously constructs a geometric flow field constraint benchmark and fine-tunes the gas phase kinetic energy output intensity after adjusting the impedance. These two paths converge to use axial suction pressure to offset melt drop fluctuations. After offsetting, the system locks the energy density of the atomization center area. This node is associated to the left to avoid the risk of melt backflow, and to the right, it is connected to the induced draft fan by controlling the pressure gradient in the gas atomization chamber. Finally, the control result suppresses the drift of the center position of the reflux zone.

[0030] Example 4: Under conditions where the electrode induction gas atomization production line operates continuously for over 200 hours, the formation of a physical oxide layer on the surface of the induction coil causes a 15% nonlinear shift in the equivalent mutual inductance impedance of the induction melting load. This results in the molten metal flow rate deviating from the preset breakage range due to the frequency pulsation of the electromagnetic field. To address the challenge of flow rate instability caused by equipment wear, the system executes a discretized compensation procedure for the induced current to the pneumatic load, utilizing a current sensor with a sampling accuracy better than 0.05A to acquire the real-time current value I of the induction coil. real And calculate the real-time current value I. real Compared with the preset reference current value I baseThe current deviation rate ΔI is determined. When the current deviation rate ΔI exceeds the calibration threshold of 3.5% for five consecutive sampling periods, the control unit corrects the proportional valve opening S of the air supply system according to the pressure compensation operator K. The calculation logic follows the formula: S = S base +K·ΔI, where S is the corrected proportional valve opening, S base The initial opening is set, K is the pressure compensation operator, and in this embodiment, its value is set to 0.18 based on the viscosity of the titanium alloy melt. ΔI is the current deviation rate. The calculation logic is used to compensate the melting power lost due to load fluctuations in real time as the negative pressure gradient increment at the end of the copper nozzle, so that the dynamic response time of the axial suction pressure is maintained within 15ms, thereby offsetting the change in melt jet diameter caused by melting efficiency pulsation.

[0031] To address the potential wall adhesion issue caused by high-temperature molten droplets contacting the inner wall of the atomizer under unsteady flow field conditions, the system initiates a physical trajectory monitoring procedure based on complex impedance phase analysis. This involves real-time monitoring of the induced current phase angle θ of the sensing unit on the inner wall of the copper nozzle, and establishing a mapping function between the phase angle θ offset and the metal adhesion thickness. When the phase angle θ offset rate exceeds 0.5 rad / s and the absolute value of the phase deviation reaches 12.0°, the system identifies this state as the initial physical fingerprint of droplet wall adhesion and increases the operating frequency of the induced draft fan from 40 Hz to 55 Hz. This increases the suction pressure difference in the negative pressure gradient zone, using the enhanced gas phase constraint force to force the titanium alloy droplets in the initial stage of droplet breakage away from the wall surface. The central axis converges, and this step utilizes quantified impedance characteristic points to replace the judgment method that relies on visual observation. This achieves a stable yield of titanium alloy powder with a particle size of less than 45μm at 56.5% under extreme fluctuations in induced power, with no condensate accumulation on the walls inside the atomization chamber. The adaptive adjustment logic of the proportional valve opening S and the impedance monitoring mechanism based on the phase angle θ work together to construct a closed-loop energy countermeasure system against electromagnetic induction thermal field fluctuations at the source of metal droplet breakage. By mapping the discrete changes in electrical parameters to physical compensation of the gas phase pressure gradient in real time, the melt breakage behavior is controlled by a deterministic engineering path composed of geometric reference and electrical feedback signal, thus achieving process self-stability in the powder making process.

[0032] Example 5: In the scenario of the first furnace preparation of titanium-aluminum alloy electrodes, the initial impedance reference of the induction melting circuit shifts due to differences in the physical properties of the raw materials. The system then executes an adjustment based on the induced current reference I. base The pre-calibration procedure involves starting the induction coil and entering the preheating stage after the atomization chamber is filled with a protective atmosphere at a pressure of 0.12 MPa. The induction power is controlled to linearly increase from 0 kW to 150 kW and maintained in steady state for 300 s. The average current within the preset sampling window is calculated by real-time acquisition of discrete sampling points of the induced current and performing a moving average operation to establish the preset reference current value I. baseSimultaneously, the air pressure difference at the bottom of the atomizing chamber is monitored to calibrate the initial static pressure state corresponding to the geometric coupling ratio R.

[0033] When the system faces a situation where the dynamic characteristics of the flow field change due to the replacement of copper nozzle components with different geometric specifications, the system executes the on-site commissioning procedure of the pressure compensation operator K, opening the proportional valve of the gas supply system to the initial set opening S before formal melting. base By sending a pressure disturbance command with a step amplitude of 0.2MPa to the air supply circuit and simultaneously recording the response deviation value of the negative pressure gradient at the end of the copper nozzle, the value of the pressure compensation operator K is determined by fitting the curve of its second derivative with the current deviation rate ΔI. During this debugging process, the single adjustment increment of the proportional valve opening S is controlled within the range of 1% to 3% of the preset range, and the flow field impedance matching process is corresponding to a closed-loop tuning path controlled by real-time physical measurement.

[0034] Example 6: In the preparation of titanium-aluminum-niobium alloy powder after replacing the induction coil assembly, the initial mutual inductance efficiency is offset due to the machining tolerance of the induction coil geometry. The system executes a standardized physical parameter self-calibration procedure to establish a control benchmark. The sampling strategy of this procedure is as follows: a circular queue with a length of 1024 sampling points is established in the buffer, the moving average window size is set to 256 sampling points, and the window overlap rate is set to 50%. Whenever 128 new current data points are collected, outlier data in the buffer that deviate from the mean by more than three times the standard deviation are removed, and the effective value of the current in the window is recalculated as the current benchmark current value to ensure the smoothness of the control command; the sampling frequency f of the current acquisition system is set. s At a frequency of 10kHz, while maintaining an argon pressure of 0.1MPa within the atomization chamber and a constant induction power of 100kW in a non-melting state, the real-time current value I was continuously collected for 1000 cycles. real The peak envelope data is extracted, and the preset reference current value I is determined by calculating the root mean square value of the peak envelope within a preset time window. base Meanwhile, the system uses a pressure sensor installed at the bottom of the atomization chamber to monitor the amplitude of the negative pressure ripple. When its standard deviation is less than 0.01 MPa, the system locks the geometric flow field constraint benchmark under the current working condition.

[0035] When the system encounters an objective change in the viscosity of the alloy melt from 5.2 mPa·s to 5.8 mPa·s, the system executes the second-order correction mode of the pressure compensation operator K. After preheating, it sends a pulse air pressure command with a step amplitude of 0.15 MPa to the air supply circuit through the proportional valve, and simultaneously records the dynamic response amplitude ΔP of the negative pressure gradient at the end of the copper nozzle. v Using the dynamic response amplitude ΔP vThe pressure compensation operator K is iteratively tuned by the ratio of the current deviation rate ΔI. When the value of the pressure compensation operator K is tuned to 0.21 through multiple steps, the axial suction pressure generated at the end of the copper nozzle and the fluctuation component of the melt mass flow rate achieve physical phase offset. Under this procedure, the proportion of fine powder with a particle size of less than 45μm in the titanium alloy powder produced is stable at 58.4%, and there is no backflow splashing phenomenon in the primary crushing area.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for coordinated control of the gas atomization fluid field of titanium alloy powder for additive manufacturing, characterized in that, Includes the following steps: Step S101: Establish a spatial interference reference between the induction melting load and the atomizing nozzle. Set the nozzle angle of the atomizer to 35° to 45°. Perform three-dimensional interference positioning on the intersection point of the copper nozzle end and the annular airflow to establish the spatial position of the atomization center area. Step S102: Determine the annular airflow gap of the air supply system and the extension length of the copper nozzle, so that the ratio of the annular airflow gap to the extension length of the copper nozzle meets the preset geometric coupling ratio, and use the Venturi effect generated by the airflow flowing through the annular constraint channel to generate a negative pressure gradient region with pressure compensation characteristics at the end of the copper nozzle. Step S103: Real-time acquisition of power drift data of induction melting load, determination of melt flow rate pulsation through mapping function of power drift data and melt mass flow rate, and adjustment of loop impedance of gas supply system according to pulsation to fine-tune output intensity of gas phase kinetic energy, and use axial suction pressure generated in negative pressure gradient zone to offset melt falling pressure fluctuation caused by pulsation. Step S104: The output intensity of gas phase kinetic energy is synchronously adjusted according to the real-time output power of the induction melting load, so that the energy density of the atomization center region is maintained above the critical value of titanium alloy droplet breakage. The localization control of the titanium alloy droplet breakage area is achieved through the physical constraint of spatial position.

2. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, In step S102, the geometric coupling ratio ranges from 5 to 12. The negative pressure gradient region uses the pressure difference in the annular constraint channel to convert the gas phase pressure energy into a suction force for the melt falling process, in order to compensate for the flow field pulsation in the atomization center region caused by the real-time output power fluctuation of the induction melting load.

3. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, In step S103, the mapping function obtains the real-time current value of the induction coil and multiplies the real-time current value with the impedance change rate of the induction melting load to generate a discrete sequence characterizing the melt flow rate. The opening of the proportional valve of the gas supply system is adjusted according to the discrete sequence.

4. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 3, characterized in that, When the fluctuation of the real-time current value exceeds the preset deviation threshold, the output pressure of the gas supply system is increased to keep the Weber number in the atomization center area above the critical threshold for titanium alloy melt breakage, so as to avoid melt backflow.

5. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 2, characterized in that, The geometric coupling ratio is represented by the symbol R, and its calculation formula is as follows: R=L / δ, where L is the extension length of the copper nozzle and δ is the annular airflow gap.

6. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, After performing step S104, the following step is also included: obtaining the grading pressure of the cyclone separator, establishing a dynamic correlation model between the grading pressure and the operating frequency of the induced draft fan, and controlling the pressure gradient in the gas atomization chamber by adjusting the operating frequency of the induced draft fan.

7. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, In step S101, the magnetic field distribution of the induction melting load is changed by adjusting the inter-turn spacing of the induction coil, thereby controlling the melt superheat fluctuation in the atomization center region to be below 10°C.

8. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, In step S103, the control logic for axial suction pressure also includes: monitoring the electromagnetic impedance signal of the inner wall of the copper nozzle, and increasing the external induced draft power to increase the pressure difference in the negative pressure gradient zone when the phase drift rate of the electromagnetic impedance signal conforms to the wall hanging characteristic curve.

9. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, The output pressure of the gas supply system is set to 3.0 MPa to 6.0 MPa. The self-stabilizing flow field established by the geometric coupling ratio is used to maintain the energy continuity of the titanium alloy droplet breakup process when the output pressure is 4.0 MPa to 5.0 MPa.

10. The method for coordinated control of gas atomization fluid field of titanium alloy powder for additive manufacturing according to claim 1, characterized in that, In step S104, by establishing a collaborative logic control spectrum involving the real-time output power of the induction melting load, the output pressure of the gas supply system, and the geometric coupling ratio, the optimal energy utilization node of the atomization center area is locked, so that the yield of powder with a particle size of less than 45μm meets the preset production standard.

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