High-precision laser additive manufacturing method and device based on metal powder melting

Abstract

The invention provides a high-precision laser additive manufacturing method and device based on metal powder melting, and relates to the technical field of metal additive manufacturing, and the high-precision laser additive manufacturing device comprises a multi-element powder supply and electrification unit which is used for carrying out independent metering supply and airflow dispersion mixing on various metal powder in an inert atmosphere environment and enabling powder particles to obtain controllable charges; the electromagnetic field cooperative control unit is used for actively regulating and controlling the falling speed and the transverse track of the powder particles through the cooperative effect of a longitudinal magnetic field and a transverse electric field when the powder particles are in a charged state; the invention provides a metal powder forming technology path based on particle size active conveying and spatial positioning, and active conveying and accurate positioning of the metal powder particles in the flying process are realized by performing electrified regulation and control on single or small-scale metal powder particles and utilizing the action of an electromagnetic field. Therefore, layer-by-layer stacking forming is completed under the condition of not depending on the whole powder laying layer.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, and in particular to a high-precision laser additive manufacturing method and apparatus based on metal powder melting. Background Technology

[0002] Metal powder additive manufacturing technology, through a layer-by-layer deposition method, has overcome the limitations of traditional machining in manufacturing complex structures and significantly reduces material waste, making it a core technology for high-end equipment manufacturing. Currently, commonly used metal powder forming technologies include selective laser melting (SLM), electron beam melting (EBM), and plasma spraying. However, in practical applications, these technologies all face core challenges related to precision, efficiency, cost, and reliability, hindering their widespread adoption in the manufacturing of precision components. SLM (Silicon-Laser Melting) technology uses lasers to scan powder layers point by point to achieve deposition. Although it can achieve an accuracy of ±20μm, it suffers from low forming efficiency, poor material utilization, and poor particle size adaptability. EBM (Electron Beam Microscopy) technology uses a high-energy electron beam as a heat source. Although it has a high deposition rate, the equipment is expensive and requires operation in a high vacuum environment. Plasma spraying technology is used for coating manufacturing, but it is limited by the forming dimensions, accuracy, and mechanical properties, and cannot meet the requirements for high precision and load-bearing capacity. It is mainly used for non-load-bearing structural components. To overcome the bottlenecks of existing technologies, this invention proposes an innovative metal powder forming technology. Through a synergistic heating mode combining electromagnetic field drive and laser preheating, it achieves precise coordination of "particle delivery – positioning – melting." This technology overcomes the precision limitations of plasma spraying, supports the independent forming of three-dimensional components, and enables higher dimensional accuracy and better mechanical properties, meeting the manufacturing requirements of precision load-bearing structures. Summary of the Invention

[0003] The purpose of this invention is to solve the problems of limited precision caused by relying on layer-by-layer powder laying in existing metal powder additive manufacturing technology, as well as the problems of excessive heat-affected zone and difficulty in forming complex structures. It provides a precision metal powder additive manufacturing technology based on electromagnetic field collaborative control, which achieves efficient forming of micro-scale high-precision components by realizing the charging, acceleration, positioning and melting control of metal powder particles.

[0004] Compared with existing mainstream additive manufacturing technologies (SLM / EBM / DED), SLM relies on layer-by-layer powder deposition to achieve melt stacking, which limits the range of powder particle sizes that can be used. When powders of different materials and particle sizes are mixed, they are prone to agglomeration or insufficient packing density, making it difficult to achieve uniform mixing and precise gradient melting. Moreover, the molding accuracy is constrained by the uniformity of powder deposition and the alignment error between layers. Although EBM relies on a vacuum environment to avoid material oxidation, it requires high-temperature preheating (600-1000℃), resulting in low production efficiency. It is also difficult to focus and refine the electron beam spot, resulting in poor molding accuracy. Furthermore, it is only suitable for conductive materials. When mixing multiple powders, the powder is prone to collapse due to the kinetic energy of the electron beam, making it impossible to achieve stable gradient control. Although DED can attempt multi-material deposition, the powder utilization rate during powder feeding is low (only 20-75%), and excess mixed powder is difficult to separate and recover. In addition, it has a large thermal gradient, high surface roughness, and discontinuous gradient transition, which cannot meet the manufacturing requirements of high-precision functional gradient components. This invention, through the multi-powder supply and charging unit described in claim 2, utilizes multiple independent storage bins adapted to metal powders of different materials and particle sizes. A Venturi-type airflow dispersion device (introducing 0.1–0.3 MPa inert argon gas) ensures thorough dispersion and mixing of the powders. Real-time feedback from the triboelectric charging roller and charge density sensor ensures uniform and controllable charge on the powder particles. Furthermore, through the electromagnetic field co-control unit described in claim 3, the synergistic effect of the longitudinal magnetic field and transverse electric field, combined with a particle size-based nonlinear correction factor and delay compensation algorithm, achieves precise control of the powder particle falling speed and transverse trajectory, enabling layer-by-layer stacking without relying on a powder layer. Simultaneously, the synchronous control unit described in claim 6 automatically generates a co-control parameter table for the multi-powder supply ratio, electromagnetic field parameters, laser power, and substrate temperature based on the material gradient requirements of the component's three-dimensional model. It dynamically adjusts the operating parameters of each unit, enabling precise gradient melting and metallurgical bonding of different powders during the molding process through the laser preheating unit described in claim 4. This fundamentally solves the problems associated with SLM, EBM, and DED. The core challenges of uniform mixing of multiple powders and stability of gradient molding have been addressed by further improving molding accuracy through particle-level closed-loop control, which can meet the manufacturing requirements of complex gradient functional components.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a high-precision laser additive manufacturing apparatus based on metal powder melting, comprising: The multi-component powder supply and charging unit is used to independently meter and supply various metal powders, disperse and mix them in an airflow, and give the powder particles a controllable charge in an inert atmosphere. The electromagnetic field coordinated control unit is used to actively regulate the falling speed and lateral trajectory of powder particles in a charged state by the synergistic effect of the longitudinal magnetic field and the transverse electric field, and to provide real-time feedback of powder particle trajectory information. The laser preheating unit is used to preheat the corresponding area before the powder particles reach the substrate based on the predicted landing point coordinates and arrival time of the powder particles, and to provide real-time feedback on the temperature information of the preheated area. The substrate forming unit is used to receive powder particles under preheating conditions and realize their instantaneous melting and layer-by-layer deposition and forming, and simultaneously feed back substrate forming status information; The synchronous control unit is connected to each of the above units to construct a multi-parameter collaborative closed-loop control system with the "powder prediction landing point and molten zone spatial alignment error" as the core control objective. The synchronous control unit receives particle trajectory information from the electromagnetic field co-control unit, temperature information from the laser preheating unit, and forming status information from the substrate forming unit. It then adjusts the feeding ratio of the multi-element powder supply to the charged unit, the field strength parameters of the electromagnetic field co-control unit, and the power parameters of the laser preheating unit in a coordinated manner. This ensures that the spatial alignment error between the predicted powder particle landing point and the substrate melting zone is ≤ ε. s (ε) s To achieve the maximum permissible spatial alignment error threshold, precise powder particle injection and stable melt molding are thus achieved.

[0006] In a preferred embodiment, the multi-element powder supply and charging unit includes multiple independently configured metal powder storage bins, a precision metering and conveying assembly, a Venturi-type airflow dispersion device, and a charging cavity; Each of the aforementioned storage bins is made of wear-resistant and non-adhesive metal material, and is adapted to metal powders of different materials or particle sizes. An inert gas replacement port is provided at the top, and an electromagnetic vibration metering and conveying assembly is integrated at the bottom to achieve stable and controllable powder output. The airflow dispersion device is a Venturi-type airflow mixing structure. It fully disperses and mixes powders from different sources by introducing inert argon gas at 0.1 to 0.3 MPa. Its outlet is connected to the charged cavity through an insulated low-friction pipe. Multiple sets of parallel-arranged triboelectric rollers are installed inside the charged cavity to triboelectrically charge the incoming powder particles. A charge density sensor is also installed inside the charged cavity, and the charge density sensor is connected to the synchronous control unit to realize real-time monitoring and dynamic adjustment of the charging state of the powder particles.

[0007] In one preferred embodiment, the electromagnetic field cooperative control unit includes a Helmholtz coil, two sets of parallel electrode plates, and a high-precision high-voltage power supply; The Helmholtz coil is located below the charged cavity and connected to an adjustable DC power supply. It is used to form a stable longitudinal magnetic field in the direction of powder particle falling, so that the charged powder particles can be directionally accelerated under the action of Lorentz force. The two sets of parallel electrode plates are symmetrically arranged on both sides of the powder particle falling channel and connected to a high-precision high-voltage power supply to form a transverse electric field. The transverse offset of the charged powder particles can be precisely controlled by adjusting the voltage of the electrode plates. When adjusting the transverse electric field strength, the synchronous control unit introduces a method based on the powder particle size. Nonlinear correction factor The control relationship is as follows: , Based on the transverse electric field strength, For reference particle size, The adjustment coefficient is obtained through experimental calibration; The parallel electrode plate has a built-in linear displacement sensor for real-time acquisition of powder particle trajectory offset information, and the information is synchronously output to the laser preheating unit and the synchronization control unit. The synchronous control unit uses the lateral displacement of powder particles obtained from a linear displacement sensor. and the instantaneous velocity of the particles in the longitudinal magnetic field. The transverse electric field control voltage is determined according to the following delay compensation relationship. : , As the reference voltage, The time it takes for powder particles to travel from the electrode plate's active area to the substrate. These are the system calibration coefficients; The synchronous control unit calculates the rate of change of trajectory curvature based on the powder particle trajectory data continuously collected by the linear displacement sensor. And dynamically adjust the rate of change of the electrode plate voltage according to the following rules: , When the trajectory curvature exceeds a preset threshold, the voltage regulation rate is reduced to suppress the oscillation of the lateral movement of powder particles.

[0008] In a preferred embodiment, the laser preheating unit includes a fiber pulse laser generator, a two-axis high-speed galvanometer scanning system, and a signal receiving unit; The signal receiving unit is connected to the linear displacement sensor signal of the electromagnetic field cooperative control unit, and is used to receive the position signal of the powder particle landing point and perform coordinate calculation. The synchronous control unit calculates the predicted impact point coordinates of powder particles based on the linear displacement sensor. and the longitudinal falling speed of the particles Calculate the laser preheating trigger advance. : , And in The two-axis high-speed galvanometer scanning system is constantly driven to preheat the predicted landing point area with laser. The predicted impact point coordinates of the powder particles are obtained by the signal receiving unit. The instantaneous longitudinal falling velocity of powder particles under the influence of an electromagnetic field. The distance from the current height of the powder particles to the substrate surface. The system response time required for the galvanometer system to complete positioning and scanning. Laser preheating refers to the time of advance triggering relative to the arrival of particles; The dual-axis high-speed galvanometer scanning system drives the laser beam to scan and preheat the target area of ​​the substrate according to the calculated coordinates, and the single laser preheating time is 1 to 5 ms. The laser preheating unit is also equipped with an infrared thermometer, which is connected to the synchronous control unit for real-time monitoring of the temperature of the preheating area and dynamic compensation of the laser power. The synchronous control unit uses the real-time temperature of the preheating area collected by the infrared thermometer. Calculate the rate of temperature change: , When the rate of temperature change exceeds the preset gradient threshold At that time, regarding laser power Perform dynamic correction: , The temperature of the preheating area is monitored in real time by an infrared thermometer. : Temperature change rate of the preheating zone : Maximum allowable temperature gradient threshold Laser preset reference power, Power compensation coefficient, obtained from system calibration.

[0009] In a preferred embodiment, the substrate forming unit includes a graphite or copper-based composite substrate, a built-in resistance heating element, a high-precision temperature sensor, and an air-floating three-axis motion platform. The resistance heating element and temperature sensor are embedded inside the substrate, forming a closed-loop temperature control system with a temperature adjustment range of 200 to 1200℃ and a temperature control accuracy of ±2℃. The air-floating three-axis motion platform is used to support the substrate and realize the layer-by-layer forming motion. Its XYZ three-axis positioning accuracy is 0.1μm, the repeatability positioning accuracy is 0.05μm, and it is connected to the synchronous control unit signal.

[0010] In one preferred embodiment, the synchronization control unit includes a PLC main controller, a high-speed industrial camera, and a control system developed based on industrial control software; At least two high-speed industrial cameras are used to collect the flight trajectory of powder particles and the state of the substrate molten area, respectively. The industrial cameras are connected to the GPU acceleration processing module. The synchronous control unit is based on the trajectory coordinates of powder particles acquired by a high-speed industrial camera. Coordinates of the center of the molten region Calculate the spatial deviation : , when and the area of ​​the molten zone Located in the set range If the current process state is deemed valid, the collaborative control parameters are maintained unchanged; otherwise, parameter correction is triggered. The predicted impact point coordinates of powder particles are acquired and calculated by an industrial camera. : Coordinates of the center of the substrate molten region Spatial deviation of the powder-molten zone : Maximum permissible spatial alignment error threshold : Current area of ​​the molten zone : The area range of the stable melting zone; The PLC main controller communicates with each functional unit via industrial Ethernet, and its core control cycle is no more than 1ms. The synchronous control unit sets rate constraints on parameter changes within adjacent control cycles: , When the predicted parameters change beyond the allowable range, a limiting adjustment is made based on the maximum rate of change. Current control cycle parameters Parameters from the previous control cycle : Maximum allowable change in a single period; The control system is used to realize three-dimensional model slicing, material gradient parameter generation, process parameter configuration, real-time status monitoring and production data storage, and automatically generate a collaborative control parameter table of material feeding ratio, electromagnetic field parameters, laser power and substrate temperature. The control system is based on the height of the 3D model slices. and the corresponding material gradient requirements Generate a set of coordinated control parameters: , It automatically generates a collaborative control parameter table according to the slice order, which can be used by the PLC for real-time calling. : No. Layer slice height, Material gradient parameters at this height. Multiple material supply ratios Longitudinal magnetic field strength Transverse electric field strength Laser power, Target substrate temperature Single-layer collaborative control parameter group; The core control objective of the synchronous control unit, "the spatial alignment error between the predicted powder landing point and the melting zone," includes the maximum permissible spatial alignment error threshold ε. s The value is flexibly set according to the precision requirements of the molded component, with a preferred range of 5–10 μm. This threshold is obtained in real time by a high-speed industrial camera mounted on the synchronous control unit, which collects the coordinates of the powder particle flight trajectory and the center coordinates of the substrate melting area. After the spatial deviation Δs is calculated by the GPU acceleration processing module, dynamic calibration is performed to ensure that Δs is always ≤ ε during the molding process. s This ensures precise particle-level injection and stable melt molding results.

[0011] As a preferred embodiment, a high-precision laser additive manufacturing method based on metal powder melting, using the high-precision laser additive manufacturing apparatus based on metal powder melting as described in any one of claims 1-6, includes the following steps: S1. Preliminary preparation: Metal powders of different materials or particle sizes are loaded into the corresponding storage bins. The three-dimensional model of the component and the material gradient requirements are imported. The powder feeding ratio parameters are generated by the synchronous control unit. The sealed door is closed and inert gas is filled in to make the molding cavity a low-oxygen inert atmosphere. At the same time, the substrate heating system, electromagnetic field system, laser system and visual perception system are started for preheating and self-inspection. S2. Powder charging feeding: The synchronous control unit drives the metering and conveying component to feed metal powder according to the feeding ratio. After the powder is dispersed by inert gas, it enters the charging cavity. The powder particles are charged by friction to obtain a uniform and stable charge, and the charging state is dynamically adjusted based on charge density feedback. S3. Electromagnetic field driven positioning: Charged powder particles enter the electromagnetic field coordinated control area, accelerate under the action of the longitudinal magnetic field, and dynamically adjust the trajectory of the particles under the action of the transverse electric field to achieve precise control of the landing position of the powder particles. At the same time, the particle position information is sent to the laser preheating unit. S4. Laser preheating: The laser preheating unit performs rapid laser preheating on the corresponding area before the powder particles reach the substrate based on the received particle landing point information, and adjusts the laser power in real time based on temperature feedback to stabilize the local temperature of the substrate in a suitable melting range. S5. Substrate melting and deposition and motion forming: The preheated powder particles melt instantly under the combined effect of substrate heat conduction and laser residual heat, forming a metallurgical bond with the substrate or the formed layer; The synchronous control unit drives the three-axis motion platform to move along the slicing path, and adjusts the substrate height after completing one layer of deposition, and executes the cycle to achieve the layer-by-layer forming of the three-dimensional component. S6. Synchronous closed-loop regulation: During the molding process, the visual perception system collects information on the powder flight trajectory and melting state in real time. The synchronous control unit adjusts the electromagnetic field parameters, laser power and substrate temperature in conjunction with the detection results to build a multi-parameter collaborative closed-loop control. S7. After molding, the component is cooled in a controlled manner under an inert atmosphere. After cooling to a safe temperature, the component is separated from the substrate and residual powder is cleaned to obtain the molded component.

[0012] As a preferred embodiment, based on step 1, argon gas is introduced into the storage bin through an inert gas replacement port to maintain a slightly positive pressure inside the bin, so as to prevent the powder from absorbing moisture and clumping. Based on step 3, the acceleration process of charged powder particles in the longitudinal magnetic field region is monitored and calibrated in real time by a velocity measuring device.

[0013] As a preferred implementation, based on step 4, when the temperature of the laser preheating area deviates from the preset temperature range, the synchronous control unit adjusts the laser power to compensate. Based on step 5, the motion speed of the three-axis motion platform is matched with the falling frequency of powder particles to ensure consistent interlayer forming.

[0014] In a preferred embodiment, based on step 7, the separation of the component from the substrate is completed by wire cutting, and the residual powder on the surface of the component is removed by gas purging. Based on step 2, the feeding ratio of multi-material powders is automatically generated and adjusted by the synchronous control unit according to the material gradient requirements of the three-dimensional model of the component.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention proposes a metal powder forming technology path based on particle-level active conveying and spatial positioning. By controlling the charge of single or small-scale metal powder particles and using electromagnetic fields, active conveying and precise positioning are achieved during flight, thereby completing layer-by-layer stacking without relying on an overall powder layer.

[0016] This invention enables real-time control of the falling speed and lateral trajectory of metal powder particles by imparting a controllable charge to the particles and introducing the synergistic effect of a longitudinal magnetic field and a transverse electric field, thereby achieving active control of the particle landing point.

[0017] This invention is based on the predicted landing point and arrival time of powder particles. Before the powder particles reach the substrate, the corresponding area is preheated by laser. The spatial alignment error between the predicted landing point of the powder and the center of the molten zone is used as the control target. The electromagnetic field parameters and the laser preheating parameters are adjusted in a linked manner to construct a closed-loop control mechanism with multi-physics coupling. Attached Figure Description

[0018] Figure 1 This invention provides a structural schematic diagram of a high-precision laser additive manufacturing method and apparatus based on metal powder melting. Figure 2 The flowchart shows a high-precision laser additive manufacturing method and apparatus based on metal powder melting provided by the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0020] Please see Figure 1-2 This invention provides a technical solution: a high-precision laser additive manufacturing device based on metal powder melting, comprising: The multi-component powder supply and charging unit is used to independently meter and supply various metal powders, disperse and mix them in an airflow, and give the powder particles a controllable charge in an inert atmosphere. The electromagnetic field coordinated control unit is used to actively regulate the falling speed and lateral trajectory of powder particles in a charged state by the synergistic effect of the longitudinal magnetic field and the transverse electric field, and to provide real-time feedback of powder particle trajectory information. The laser preheating unit is used to preheat the corresponding area before the powder particles reach the substrate based on the predicted landing point coordinates and arrival time of the powder particles, and to provide real-time feedback on the temperature information of the preheated area. The substrate forming unit is used to receive powder particles under preheating conditions and realize their instantaneous melting and layer-by-layer deposition and forming, and simultaneously feed back substrate forming status information; The synchronous control unit is connected to each of the above units to construct a multi-parameter collaborative closed-loop control system with the "powder prediction landing point and molten zone spatial alignment error" as the core control objective. The synchronous control unit receives particle trajectory information from the electromagnetic field co-control unit, temperature information from the laser preheating unit, and forming status information from the substrate forming unit. It then adjusts the feeding ratio of the multi-element powder supply to the charged unit, the field strength parameters of the electromagnetic field co-control unit, and the power parameters of the laser preheating unit in a coordinated manner. This ensures that the spatial alignment error between the predicted powder particle landing point and the substrate melting zone is ≤ ε. s (ε) s To achieve the maximum permissible spatial alignment error threshold, precise powder particle injection and stable melt molding are thus achieved.

[0021] like Figure 1-2 As shown, the multi-element powder supply and charging unit includes multiple independently set metal powder storage bins, a precision metering and conveying assembly, a Venturi-type airflow dispersion device, and a charging cavity; Each storage silo is made of wear-resistant and non-adhesive metal material, and is adapted to metal powders of different materials or particle sizes. It is equipped with an inert gas replacement interface at the top and an electromagnetic vibration metering and conveying assembly at the bottom to achieve stable and controllable powder output. The airflow dispersion device is a Venturi-type airflow mixing structure. It fully disperses and mixes powders from different sources by introducing inert argon gas at 0.1 to 0.3 MPa. Its outlet is connected to the charged cavity through an insulated low-friction pipe. Multiple sets of parallel-arranged triboelectric rollers are installed inside the electrified cavity to triboelectrically electrify the incoming powder particles. A charge density sensor is also installed inside the electrified cavity, and the charge density sensor is connected to the synchronous control unit to realize real-time monitoring and dynamic adjustment of the electrification state of the powder particles.

[0022] Specifically, a multi-metal powder supply system enables stable, continuous, and controllable output of metal powders of different materials or particle sizes. An airflow dispersion device effectively breaks up powder agglomeration and improves dispersion uniformity. On this basis, the powder acquires a controllable charge through a triboelectric structure in the charged cavity. Its charging state can be monitored in real time by a charge density sensor and fed back to the synchronous control unit for dynamic adjustment. Through the coordinated control of powder supply, dispersion state, and charging characteristics, this embodiment can significantly reduce state fluctuations before the powder enters the subsequent conveying and forming stages, improve the controllability of the powder conveying process and the stability of system operation, thereby providing a reliable guarantee for high-precision and high-consistency metal additive manufacturing.

[0023] like Figure 1-2 As shown, the electromagnetic field co-control unit includes a Helmholtz coil, two sets of parallel electrode plates, and a high-precision high-voltage power supply. A Helmholtz coil is placed below the charged cavity and connected to an adjustable DC power supply. It is used to form a stable longitudinal magnetic field in the direction of powder particle falling, so that the charged powder particles can be directionally accelerated under the action of Lorentz force. Two sets of parallel electrode plates are symmetrically arranged on both sides of the powder particle falling channel and connected to a high-precision high-voltage power supply to form a transverse electric field. The transverse offset of the charged powder particles is precisely controlled by adjusting the voltage of the electrode plates. When adjusting the transverse electric field strength, the synchronous control unit introduces a method based on the powder particle size. Nonlinear correction factor The control relationship is as follows: , Based on the transverse electric field strength, For reference particle size, The adjustment coefficient is obtained through experimental calibration; The parallel electrode plate has a built-in linear displacement sensor for real-time acquisition of powder particle trajectory offset information, and synchronously outputs the information to the laser preheating unit and the synchronous control unit. The synchronous control unit uses the lateral displacement of powder particles obtained from a linear displacement sensor. and the instantaneous velocity of the particles in the longitudinal magnetic field. The transverse electric field control voltage is determined according to the following delay compensation relationship. : , As the reference voltage, The time it takes for powder particles to travel from the electrode plate's active area to the substrate. These are the system calibration coefficients; The synchronous control unit calculates the rate of change of trajectory curvature based on powder particle trajectory data continuously acquired by a linear displacement sensor. And dynamically adjust the rate of change of the electrode plate voltage according to the following rules: , When the trajectory curvature exceeds a preset threshold, the voltage regulation rate is reduced to suppress the oscillation of the lateral movement of powder particles.

[0024] Specifically, by installing linear displacement sensors within the parallel electrode plates, the trajectory offset information of powder particles is acquired in real time and synchronously fed back to the laser preheating unit and the synchronization control unit. This enables the system to dynamically adjust the powder during flight by combining feedforward and feedback. The synchronization control unit precisely corrects the transverse electric field voltage based on the lateral offset of the powder particles and their instantaneous velocity in the longitudinal magnetic field using a delay compensation relationship. Furthermore, it adaptively suppresses the voltage change rate by incorporating the trajectory curvature change rate, thereby effectively reducing lateral motion oscillations of the powder particles and improving trajectory stability. Simultaneously, an alternating Holtz coil forms a stable longitudinal magnetic field, enabling directional acceleration of charged powder particles under the Lorentz force. Combined with the adjustable transverse electric field generated by the two sets of parallel electrode plates, this achieves precise control of the lateral displacement of the powder particles. Furthermore, a nonlinear correction factor based on the powder particle size is introduced to adaptively adjust the transverse electric field strength according to particle size, reducing the differences in force response between powders of different sizes. Through the above-mentioned multi-sensor information fusion, electromagnetic field coordinated regulation, and nonlinear compensation control, the system achieves comprehensive control.

[0025] like Figure 1-2 As shown, the laser preheating unit includes a fiber pulse laser generator, a two-axis high-speed galvanometer scanning system, and a signal receiving unit; The signal receiving unit is connected to the linear displacement sensor signal of the electromagnetic field cooperative control unit to receive the position signal of the powder particle landing point and perform coordinate calculation; The synchronous control unit calculates the predicted impact point coordinates of powder particles based on the linear displacement sensor. and the longitudinal falling speed of the particles Calculate the laser preheating trigger advance. : , And in The two-axis high-speed galvanometer scanning system is constantly driven to preheat the predicted landing point area with laser. The predicted impact point coordinates of the powder particles are obtained by the signal receiving unit. The instantaneous longitudinal falling velocity of powder particles under the influence of an electromagnetic field. The distance from the current height of the powder particles to the substrate surface. The system response time required for the galvanometer system to complete positioning and scanning. Laser preheating refers to the time of advance triggering relative to the arrival of particles; The two-axis high-speed galvanometer scanning system drives the laser beam to scan and preheat the target area of ​​the substrate according to the calculated coordinates. The single laser preheating time is 1 to 5 ms. The laser preheating unit is also equipped with an infrared thermometer, which is connected to the synchronous control unit to monitor the temperature of the preheating area in real time and realize dynamic compensation of laser power. The synchronous control unit uses the real-time temperature of the preheating area collected by the infrared thermometer. Calculate the rate of temperature change: , When the rate of temperature change exceeds the preset gradient threshold At that time, regarding laser power Perform dynamic correction: , The temperature of the preheating area is monitored in real time by an infrared thermometer. : Temperature change rate of the preheating zone : Maximum allowable temperature gradient threshold Laser preset reference power, Power compensation coefficient, obtained from system calibration.

[0026] Specifically, by introducing an infrared thermometer into the laser preheating unit, the temperature of the preheating area is monitored in real time, and the synchronous control unit calculates the collected temperature T(t) and its rate of change. Dynamic compensation and adjustment of laser power effectively suppresses overheating or uncontrolled temperature rise when the rate of temperature change exceeds a preset threshold, improving the stability and safety of the preheating process. Simultaneously, the synchronous control unit, combining the predicted particle landing point coordinates and longitudinal falling velocity obtained from the linear displacement sensor, calculates the advance trigger time for laser preheating and drives the high-speed galvanometer scanning system to perform directional preheating of the target area before the particles arrive. Through the synergistic effect of the predicted landing point-based advance heating mechanism and the closed-loop power control method, this embodiment achieves precise matching between laser energy and the arrival time and spatial position of the powder, reducing instantaneous thermal shock, improving preheating uniformity and controllability, and providing a reliable guarantee for subsequent stable and high-quality metal forming processes.

[0027] like Figure 1-2 As shown, the substrate forming unit includes a graphite or copper-based composite substrate, a built-in resistance heating element, a high-precision temperature sensor, and an air-floating three-axis motion platform. The resistance heating element and temperature sensor are embedded inside the substrate, forming a closed-loop temperature control system with a temperature adjustment range of 200~1200℃ and a temperature control accuracy of ±2℃. The air-floating three-axis motion platform is used to support the substrate and realize the layer-by-layer molding motion. Its XYZ three-axis positioning accuracy is 0.1μm, the repeatability positioning accuracy is 0.05μm, and it is connected to the synchronous control unit signal.

[0028] Specifically, the temperature control system precisely maintains temperature fluctuations within ±2℃, ensuring the stability and precise control of the substrate under different temperature conditions. Simultaneously, the precise control of the air-floating three-axis motion platform enables high-precision positioning and movement of the substrate, with X, Y, and Z axis positioning accuracy reaching 0.1μm and repeatability of 0.05μm. This ensures precise operation and position control of the substrate during the molding process, effectively improving the stability and precision of the additive manufacturing process.

[0029] like Figure 1-2 As shown, the synchronous control unit includes a PLC main controller, a high-speed industrial camera, and a control system developed based on industrial control software. At least two high-speed industrial cameras are used to capture the flight trajectory of powder particles and the state of the substrate molten area, respectively. The industrial cameras are connected to the GPU acceleration processing module. The synchronous control unit is based on the trajectory coordinates of powder particles acquired by a high-speed industrial camera. Coordinates of the center of the molten region Calculate the spatial deviation : , when and the area of ​​the molten zone Located in the set range If the current process state is deemed valid, the collaborative control parameters are maintained unchanged; otherwise, parameter correction is triggered. The predicted impact point coordinates of powder particles are acquired and calculated by an industrial camera. : Coordinates of the center of the substrate molten region Spatial deviation of the powder-molten zone : Maximum permissible spatial alignment error threshold : Current area of ​​the molten zone : The area range of the stable melting zone; The PLC main controller communicates with each functional unit via industrial Ethernet, and its core control cycle is no more than 1ms. The synchronous control unit sets rate constraints on parameter changes within adjacent control cycles: , When the predicted parameters change beyond the allowable range, a limiting adjustment is made based on the maximum rate of change. Current control cycle parameters Parameters from the previous control cycle : Maximum allowable change in a single period; The control system is used to realize 3D model slicing, material gradient parameter generation, process parameter configuration, real-time status monitoring and production data storage, and automatically generate a table of coordinated control parameters for material feeding ratio, electromagnetic field parameters, laser power and substrate temperature. The control system is based on the height of the 3D model slices. and the corresponding material gradient requirements Generate a set of coordinated control parameters: , It automatically generates a collaborative control parameter table according to the slice order, which can be used by the PLC for real-time calling. : No. Layer slice height, Material gradient parameters at this height. Multiple material supply ratios Longitudinal magnetic field strength Transverse electric field strength Laser power, Target substrate temperature Single-layer collaborative control parameter group.

[0030] Specifically, by combining a PLC controller and high-precision sensors, real-time monitoring and adjustment of the deviation between the metal powder's flight trajectory and the molten zone are achieved. The control system effectively optimizes powder delivery and deposition accuracy by dynamically adjusting electric, magnetic, and laser heating parameters, combined with substrate temperature monitoring and control algorithms. Employing a closed-loop control mode, the system precisely adjusts the powder deposition point based on the real-time position and predicted trajectory of the powder particles, ensuring high precision and consistency in the molding process. By automatically adjusting material parameters and the laser preheating path, the system significantly improves the stability and quality of the molding process, making it suitable for additive manufacturing of high-performance metal components.

[0031] Working principle: Step 1: Preliminary preparation. Metal powders of different materials or particle sizes are loaded into the corresponding storage bins. The 3D model of the component and material gradient requirements are imported, and the powder feeding ratio parameters are generated by the synchronous control unit. The sealed door is closed and inert gas is introduced to make the molding cavity a low-oxygen inert atmosphere. At the same time, the substrate heating system, electromagnetic field system, laser system and visual perception system are started for preheating and self-inspection. Argon gas is introduced into the storage bin through the inert gas replacement interface to maintain a slightly positive pressure state inside the bin to prevent the powder from absorbing moisture and agglomerating. Step 2: Powder charging feeding. The synchronous control unit drives the metering and conveying component to feed metal powder according to the feeding ratio. After the powder is dispersed by inert gas, it enters the charging cavity. The powder particles are charged by friction to obtain a uniform and stable charge, and the charging state is dynamically adjusted based on charge density feedback. Step 3: Electromagnetic field driven positioning. Charged powder particles enter the electromagnetic field coordinated control area and accelerate under the action of the longitudinal magnetic field. The trajectory of the particles is dynamically adjusted under the action of the transverse electric field to achieve precise and controllable control of the powder particle landing point. At the same time, the particle position information is sent to the laser preheating unit. The acceleration process of the charged powder particles in the longitudinal magnetic field area is monitored and calibrated in real time by the speed measuring device. The feeding ratio of multi-material powders is automatically generated and adjusted by the synchronous control unit according to the material gradient requirements of the three-dimensional model of the component. Step 4: Laser preheating. The laser preheating unit performs rapid laser preheating on the corresponding area before the powder particles reach the substrate based on the received particle landing point information. It also adjusts the laser power in real time based on temperature feedback to stabilize the local temperature of the substrate within a suitable melting range. When the temperature of the laser preheating area deviates from the preset temperature range, the synchronous control unit adjusts the laser power to compensate. Step 5: Substrate melting and deposition and motion forming. The preheated powder particles melt instantly under the combined effect of the substrate's conductive heat and the laser's residual heat, forming a metallurgical bond with the substrate or the already formed layer. The synchronous control unit drives the three-axis motion platform to move along the slicing path, and adjusts the substrate height after completing one layer of deposition. This process is repeated to achieve the layer-by-layer forming of the three-dimensional component. The movement speed of the three-axis motion platform is matched with the falling frequency of the powder particles to ensure the consistency of the interlayer forming. Step 6: Synchronous closed-loop adjustment. During the molding process, the visual perception system collects information on the powder flight trajectory and melting state in real time. The synchronous control unit adjusts the electromagnetic field parameters, laser power and substrate temperature in conjunction with the detection results to build a multi-parameter collaborative closed-loop control. Step 7: After molding is completed, the component is cooled in a controlled manner under an inert atmosphere. After cooling to a safe temperature, the component is separated from the substrate and the residual powder is cleaned to obtain the molded component. The separation of the component from the substrate is completed by wire cutting, and the residual powder on the surface of the component is removed by gas purging.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-precision laser additive manufacturing apparatus based on metal powder melting, characterized by, The application relates to a multi-element powder supply and charging unit for independently metering, airflow dispersing and mixing a plurality of metal powders and making powder particles obtain controllable charges in an inert atmosphere environment. An electromagnetic field synergistic control unit is used for actively regulating the falling speed and lateral trajectory of the powder particles under the charged state of the powder particles by the synergistic effect of a longitudinal magnetic field and a transverse electric field, and real-time feedback of the powder particle trajectory information is realized. A laser preheating unit is used for preheating a corresponding area by laser before the powder particles reach the substrate based on the predicted landing point coordinates and arrival time of the powder particles, and real-time feedback of the preheating area temperature information is realized. A substrate forming unit is used for receiving the powder particles and realizing instantaneous melting and layer-by-layer accumulation forming under the preheating condition, and synchronous feedback of the substrate forming state information is realized. A synchronous control unit is respectively connected with the units, and is used for constructing a multi-parameter synergistic closed-loop control system with the powder predicted landing point and the melting area space alignment error as a core control target. The multi-element powder supply and charging unit comprises a plurality of independently arranged metal powder storage bins, accurate metering and conveying assemblies, Venturi airflow dispersing devices and charging cavities. The synchronization control unit receives the particle trajectory information of the electromagnetic field cooperative control unit, the temperature information of the laser preheating unit, and the forming state information of the substrate forming unit, and linkage adjusts the feeding proportion of the multi-element powder supply and the charging unit, the field strength parameter of the electromagnetic field cooperative control unit, and the power parameter of the laser preheating unit, so that the space alignment error of the predicted landing point of the powder particles and the molten zone of the substrate is ≤ε s (ε s is the maximum allowable space alignment error threshold), and the powder particles are precisely incident and stably fused and formed.

2. The high-precision laser additive manufacturing device based on metal powder melting according to claim 1, characterized in that: Each of the storage bins is made of wear-resistant and anti-adhesion metal materials, is adapted to metal powders with different materials or different particle sizes, is provided with an inert gas replacement interface at the top, and is integrated with an electromagnetic vibration type metering and conveying assembly at the bottom, so that stable and controllable output of the powders is realized. The airflow dispersing device is a Venturi airflow mixing structure, inert argon gas with a pressure of 0.1-0.3 MPa is introduced to sufficiently disperse and mix the powders from different sources, and the outlet of the airflow dispersing device is communicated with the charging cavity through an insulated low-friction pipeline. A plurality of parallel friction charging rollers are arranged in the charging cavity and are used for friction charging of the entering powder particles, and the charging cavity is provided with a charge density sensor which is connected with the synchronous control unit in signal connection, so that real-time monitoring and dynamic adjustment of the charged state of the powder particles are realized. The electromagnetic field synergistic control unit comprises a Helmholtz coil, two groups of parallel electrode plates and a high-precision high-voltage power supply.

3. The high precision laser additive manufacturing apparatus based on metal powder melting according to claim 1, characterized in that: The Helmholtz coil is arranged below the charging cavity and is connected with an adjustable direct current power supply, is used for forming a stable longitudinal magnetic field in the falling direction of the powder particles, and makes the charged powder particles realize directional acceleration under the action of the Lorentz force. The two groups of parallel electrode plates are symmetrically arranged on both sides of the powder particle falling channel and are connected with the high-precision high-voltage power supply, are used for forming a transverse electric field, and accurately control the transverse offset of the charged powder particles by adjusting the voltage of the electrode plates. The linear displacement sensor arranged in the parallel electrode plate is used for collecting the trajectory offset information of the powder particles in real time, and synchronously outputs the information to the laser preheating unit and the synchronous control unit. The synchronization control unit introduces a non-linear correction factor based on the powder particle size when adjusting the lateral electric field strength The control relationship is:​ , is a base lateral electric field strength, is a reference particle diameter, is an adjustment coefficient obtained by experimental calibration; When the trajectory curvature exceeds a preset threshold, the voltage adjustment rate is reduced to inhibit the oscillation of the transverse motion of the powder particles. The synchronous control unit uses the lateral displacement of powder particles obtained from a linear displacement sensor. and the instantaneous velocity of the particles in the longitudinal magnetic field. The transverse electric field control voltage is determined according to the following delay compensation relationship. : , is a reference voltage, is a time of flight of the powder particles from the electrode plate active area to the substrate, is a system calibration coefficient; The synchronous control unit calculates the trajectory curvature change rate based on the trajectory data of the powder particles continuously collected by the linear displacement sensor , and dynamically adjusts the electrode plate voltage change rate according to the following rules: , The laser preheating unit comprises a fiber pulse laser generator, a two-axis high-speed galvanometer scanning system and a signal receiving unit.

4. The high precision laser additive manufacturing apparatus based on metal powder melting according to claim 1, characterized in that: The signal receiving unit is connected with the linear displacement sensor of the electromagnetic field synergistic control unit in signal connection, is used for receiving the powder particle landing point position signal and performing coordinate calculation, and is connected with the synchronous control unit in signal connection. ​ The synchronous control unit calculates the predicted landing point coordinates of the powder particles from the linear displacement sensor and the longitudinal falling speed of the particles , and calculates the trigger advance of the laser preheating : , And in The two-axis high-speed galvanometer scanning system is driven at the moment to perform laser preheating on the predicted landing point region. : the predicted landing point coordinate of the powder particle calculated by the signal receiving unit, : the instantaneous vertical falling speed of the powder particle under the action of the electromagnetic field, : the distance from the current height of the powder particle to the surface of the substrate, : the system response time required for the galvanometer system to complete positioning and scanning, : the advance trigger time of the laser preheating relative to the arrival of the particles; The two-axis high-speed mirror scanning system drives the laser beam to scan and preheat the target area of the substrate according to the calculated coordinates, and the single laser preheating time is 1-5 ms; The laser preheating unit is also provided with an infrared temperature measuring instrument, which is signal connected with the synchronous control unit, for real-time monitoring of the preheating area temperature and realizing dynamic compensation of the laser power; The synchronous control unit calculates the temperature change rate according to the real-time temperature of the preheating area collected by the infrared thermometer . , When the temperature change rate exceeds a preset gradient threshold The laser power Dynamic correction is performed: , : temperature of preheating area monitored by infrared thermometer in real time, : temperature change rate of preheating area, : maximum temperature gradient threshold allowed, : laser preset reference power, : power compensation coefficient, obtained by system calibration.

5. The high precision laser additive manufacturing apparatus based on metal powder melting according to claim 1, characterized in that: The substrate forming unit includes a graphite or copper-based composite substrate, a built-in resistance heating element, a high-precision temperature sensor, and an air-floating three-axis motion platform; The resistance heating element and the temperature sensor are embedded in the substrate, forming a closed-loop temperature control system with a temperature regulation range of 200-1200℃ and a temperature control accuracy of ±2℃; The air-floating three-axis motion platform is used to carry the substrate and realize layer-by-layer forming movement, with XYZ three-axis positioning accuracy of 0.1μm and repeat positioning accuracy of 0.05μm, and is signal connected with the synchronous control unit.

6. The high precision laser additive manufacturing apparatus based on metal powder melting according to claim 1, characterized in that: The synchronous control unit includes a PLC main controller, a high-speed industrial camera, and a control system developed based on industrial control software; At least two high-speed industrial cameras are used to collect the flight trajectory of the powder particles and the melting area state of the substrate, and the industrial cameras are connected with a GPU acceleration processing module; The synchronous control unit calculates the spatial deviation amount based on the powder particle trajectory coordinates collected by the high-speed industrial camera with the center coordinates of the melting region , calculates the spatial deviation amount : , When and the melting zone area is located in the set interval , it is determined that the current process state is valid, and the cooperative control parameter is maintained unchanged; Otherwise, trigger parameter correction; : powder particle predicted landing coordinates as collected and resolved by the industrial camera, : substrate melt zone center coordinates, : powder to melt zone spatial deviation, : maximum allowable spatial alignment error threshold, : current melt zone area, : stable melt zone area range; The PLC main controller is communicatively connected with each functional unit through industrial Ethernet, and the core control period is not greater than 1ms; The synchronous control unit sets a rate constraint on the parameter change amount in adjacent control periods: , When the predicted parameter change exceeds the allowed range, limit adjustment is made according to the maximum change rate, : current control cycle parameter, : previous control cycle parameter, : single cycle maximum allowed variation; The control system is used to realize three-dimensional model slicing, material gradient parameter generation, process parameter configuration, real-time state monitoring and production data storage, and automatically generates a collaborative control parameter table for feed ratio, electromagnetic field parameters, laser power and substrate temperature; The control system is based on the height of the 3D model slices. and the corresponding material gradient requirements Generate a set of coordinated control parameters: , And automatically form a collaborative control parameter table according to the slicing order, for real-time calling by PLC, : first layer slice height, : material gradient parameter at the height, : multi-material feed ratio, : longitudinal magnetic field strength, : transverse electric field strength, : laser power, : target substrate temperature, : single layer coordinated control parameter group.

7. A high-precision laser additive manufacturing method based on metal powder melting, characterized by, A high-precision laser additive manufacturing device based on metal powder melting is used, including the following steps: S1, preliminary preparation, different materials or different particle sizes of metal powder are loaded into corresponding storage bins, a three-dimensional model of the component and material gradient requirements are introduced, and a powder feed ratio parameter is generated by the synchronous control unit; close the sealed cabin door and fill with inert gas to make the forming cavity in a low-oxygen inert atmosphere, and start the substrate heating system, electromagnetic field system, laser system and visual perception system for preheating and self-checking; S2, powder charging, the synchronous control unit drives the metering and conveying assembly to convey metal powder according to the feed ratio, the powder enters the charging cavity after being dispersed by inert gas, the powder particles obtain uniform and stable charge through friction charging, and the charging state is dynamically adjusted based on charge density feedback; S3, electromagnetic field driven positioning, the charged powder particles enter the electromagnetic field collaborative control area, accelerate under the action of the longitudinal magnetic field, and dynamically adjust the particle motion trajectory under the action of the transverse electric field to realize precise and controllable powder particle landing position, and simultaneously send the particle position information to the laser preheating unit. S4, laser preheating, the laser preheating unit preheats the corresponding area by laser according to the received particle landing position information before the powder particles reach the substrate, and adjusts the laser power in real time based on the temperature feedback, so that the local temperature of the substrate is stabilized in the appropriate melting interval; S5, substrate melting and motion forming, the preheated powder particles are instantaneously melted under the synergistic action of substrate conduction heat and laser residual heat, and form metallurgical bonding with the substrate or the formed layer; the synchronous control unit drives the three-axis motion platform to move according to the slicing path, and adjusts the substrate height after completing a layer of accumulation, and circulates to realize the layer-by-layer forming of three-dimensional components; S6, synchronous closed-loop adjustment, during the forming process, the visual perception system collects the powder flight trajectory and melting state information in real time, and the synchronous control unit adjusts the electromagnetic field parameters, laser power and substrate temperature according to the detection results, and constructs a multi-parameter cooperative closed-loop control; S7, after the forming is completed, the component is controlled to cool under the protection of inert atmosphere, and the component is separated from the substrate and the residual powder is cleaned after cooling to a safe temperature, and the formed component is obtained.

8. The high-precision laser additive manufacturing method based on metal powder melting according to claim 7, characterized in that: Based on step 1, the storage bin is connected to argon through an inert gas replacement interface to maintain a micro-positive pressure state in the bin to prevent powder from absorbing moisture and caking; Based on step 3, the acceleration process of charged powder particles in the longitudinal magnetic field area is monitored and calibrated in real time by a speed measuring device.

9. The high-precision laser additive manufacturing method based on metal powder melting according to claim 7, characterized in that: Based on step 4, when the temperature of the laser preheating area deviates from the preset temperature range, the synchronous control unit compensates and adjusts the laser power; Based on step 5, the motion speed of the three-axis motion platform is matched with the falling frequency of the powder particles to ensure the consistency of layer forming.

10. The high-precision laser additive manufacturing method based on metal powder melting according to claim 7, characterized in that: Based on step 7, the separation of the component and the substrate is completed by wire cutting, and the residual powder on the surface of the component is removed by gas blowing; Based on step 2, the feeding ratio of multi-material powder is automatically generated and adjusted by the synchronous control unit according to the material gradient requirement of the three-dimensional model of the component.

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