A high deposition rate additive method of magnetic pulse cutting of droplets

Abstract

This application belongs to the field of metal additive manufacturing and welding technology, and relates to a high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets. Specifically, a magnetic pulse cutting coil is placed outside the nozzle of a welding torch, and a pulsed current is passed through the magnetic pulse cutting coil during the arc additive manufacturing process to form a pulsed magnetic field. This pulsed magnetic field is used to cut the molten droplet or liquid bridge at the corresponding stage of droplet growth. The center of the magnetic pulse cutting coil is kept flush with the end face of the welding wire. This invention achieves precise control of droplet size and rapid separation by passing a pulsed current through the magnetic pulse cutting coil, allowing the generated pulsed magnetic field to directly act on the connection point of the pulsed molten droplet or the liquid bridge, thereby improving the transition speed. Furthermore, the pulsed magnetic field can instantaneously compress the arc before the droplet transition, causing the arc column to shrink, increasing energy density, reducing lateral arc oscillation, increasing local heating concentration, and reducing spatter and porosity.

Description

Technical Field

[0001] This application belongs to the field of metal additive manufacturing and welding technology, and more specifically, relates to a high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets. Background Technology

[0002] Additive manufacturing (AM) technology starts with three-dimensional topological structures and adopts a bottom-up, layer-by-layer forming method. It can not only achieve lightweight and highly integrated structural components, but also enable customized performance optimization by combining the thermal treatment response of materials. In particular, arc-DED (arc-based additive manufacturing) can naturally form heterogeneous structures with spatially distributed gradients through its multi-pass, multi-layer deposition process. This allows materials to potentially exhibit a "self-reinforcing" effect during service. That is, under cyclic loading, local mechanical properties are improved through dislocation evolution and precipitate phase changes, which is an advantage that is difficult to achieve with traditional manufacturing processes.

[0003] However, existing arc-DED processes still face significant challenges in achieving a balance between high deposition rate and high forming accuracy. For example, during the growth and transition of pulsed droplets, the diameter is often large and the time is long, which causes a large-scale impact on the molten pool, easily leading to local overheating, increased spatter, and decreased forming accuracy. During short-circuit transition, the long-term contact between the droplet and the molten pool will significantly increase local heat input, inducing defects such as porosity and coarsening of the microstructure. In related fields, existing technologies have attempted to introduce magnetic fields or multi-physics coupling methods to improve the forming quality of arc-DED. However, the control targets of these methods are all concentrated on the internal flow of the molten pool, lacking direct effects on droplet generation, size control, and rapid transition. For example, Chinese patent application CN202510204204.5 discloses a magnetically controlled arc filament additive manufacturing system, but its composite magnetic field mainly acts on the molten pool, refining grains and improving performance through stirring, but does not directly control the generation and transition of droplets. It cannot avoid the decrease in forming accuracy caused by the impact of large-sized droplets on the molten pool. Chinese patent application CN202410601387.X discloses an arc additive manufacturing technology assisted by an ultrasonic forging composite magnetic field. Its longitudinal magnetic field also mainly acts on the molten pool, improving the uniformity of the structure and reducing porosity by combining with ultrasonic forging. However, the defect suppression mechanism depends on the internal flow and cavitation effect of the molten pool, and the control of the heat input of the droplets is insufficient. There is still a risk of surface quality degradation in high-precision, small-size, or thin-walled structure forming.

[0004] Against this backdrop, there is an urgent need to develop an additive manufacturing method that can precisely control the droplet size, accelerate the droplet transition speed, and improve arc stability during the arc-DED process. Summary of the Invention

[0005] In response to the deficiencies or improvement needs of existing technologies, this application provides a high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets, aiming to solve the technical problems of uncontrollable droplet size, slow transition rate, excessive heat input, and insufficient arc stability in the existing arc-DED process.

[0006] This application provides a high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets. Specifically, a magnetic pulse cutting coil is set outside the nozzle of a welding torch, and a pulse current is passed into the magnetic pulse cutting coil during the arc additive manufacturing process to form a pulse magnetic field. The pulse magnetic field is used to cut the molten droplet or liquid bridge at the corresponding stage of droplet growth. The center of the magnetic pulse cutting coil is kept flush with the end face of the welding wire.

[0007] As a further preferred embodiment, the cutting of the molten droplet or liquid bridge at the corresponding stage of droplet growth includes: During the EP phase, when the current and voltage of each sub-cycle of the pulsed current are at their peak, the pulsed magnetic field cuts the molten droplet; during the EN phase, when the short-circuit duration reaches a preset threshold, the pulsed magnetic field cuts the liquid bridge.

[0008] As a further preferred embodiment, the method includes the following steps: S1, setting a magnetic pulse cutting coil on the outside of the nozzle of the welding gun; S2. Perform arc additive manufacturing according to the set process parameters, feed the welding wire to the designated position of the workpiece on the substrate and start the arc to form a molten pool, and at the same time pass the pulse current into the magnetic pulse cutting coil to form a pulse magnetic field, and cut the molten drop or liquid bridge at the corresponding stage of droplet growth. S3. Move the welding wire along the specified path to perform arc additive manufacturing. During this process, adjust the magnetic pulse cutting coil in real time to ensure that the center of the magnetic pulse cutting coil remains flush with the end face of the welding wire.

[0009] As a further preferred embodiment, the welding wire comprises a high-strength aluminum alloy welding wire of Al-Zn-Mg-Cu system with a diameter of 0.8~1.6 mm, and the substrate comprises a pure aluminum plate with a thickness of 5~20 mm.

[0010] As a further preferred embodiment, the welding wire and the substrate are pretreated before arc additive manufacturing. The pretreatment includes removing the oxide film, oil and impurities on the surface of the substrate by mechanical grinding and / or chemical cleaning, and placing the welding wire and the substrate in an oven for heat preservation at a temperature of 80±5℃ for a duration of not less than 6 hours.

[0011] As a further preferred embodiment, the process parameters include the travel speed of the electric arc heat source, the wire feeding speed of the welding wire, the purity of the shielding gas, and also the maximum excitation current, duration, and delay time of the magnetic pulse cutting coil.

[0012] As a further preferred embodiment, the magnetic pulse cutting coil employs an independent control module to monitor the dynamic curve of the pulse current and voltage in real time, and performs pulsed magnetic field cutting of the molten droplet at regular intervals.

[0013] As a further preferred embodiment, the method further includes providing an arc compression coil outside the nozzle of the welding torch, and supplying a stable voltage DC current to the arc compression coil during the arc additive manufacturing process.

[0014] As a further preferred option, the molten droplets deposited on the substrate are provided with an interlayer temperature of 100±20℃, or an interlayer interval waiting time of 2-4 min, or rapid cooling of the next layer before depositing the next layer.

[0015] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. Due to the design of the magnetic pulse cutting coil and the fact that the center of the magnetic pulse cutting coil is kept flush with the end face of the welding wire, when a pulse current is passed through the magnetic pulse cutting coil, the pulse magnetic field generated directly acts on the pulse droplet connection or liquid bridge, realizing precise control and rapid separation of the droplet size and improving the transition speed. Moreover, the pulse magnetic field can also instantaneously compress the arc before the droplet transition, causing the arc column to shrink and the energy density to increase. At the same time, it reduces the lateral oscillation of the arc, increases the local heating concentration, and reduces spatter and porosity, thereby improving the surface finish and dimensional accuracy of the formed surface. This invention reduces the impact of the droplet on the molten pool and the heat input from the source, reduces spatter and porosity generation, and inhibits the coarsening of the structure. While ensuring a high deposition rate, it achieves ultra-precision forming. While maintaining the high efficiency of arc-DED, it can significantly improve the surface quality and structure uniformity of thin-walled, small-sized and complex structural parts, extend the service life of electronic products, and expand the application scope of arc-DED in the field of high-end manufacturing.

[0016] 2. This application preferably uses Al-Zn-Mg-Cu welding wire. Al-Zn-Mg-Cu is a high-strength aluminum alloy material with extremely high specific strength and excellent corrosion resistance and heat treatment response performance. It has significant application advantages over traditional aluminum alloys in aerospace, transportation, and high-end electronic product appearance parts and support structures.

[0017] 3. By passing a stable voltage DC current through the arc compression coil, a low-amplitude DC magnetic field can be generated to compress the arc, thereby reducing the lateral oscillation of the arc, improving energy concentration, and reducing the impact of external interference on forming accuracy. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the equipment layout for a high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets, provided in an embodiment of this application. In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 10. Welding torch; 20. Welding wire; 30. Magnetic pulse cutting coil; 40. Substrate; 50. Workpiece; 11. Nozzle. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] This application provides a high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets. Specifically, a magnetic pulse cutting coil 30 is set outside the nozzle of the welding torch 10, and a pulse current is passed into the magnetic pulse cutting coil 30 during the arc additive manufacturing process to form a pulse magnetic field. The pulse magnetic field is used to cut the molten droplet or liquid bridge at the corresponding stage of droplet growth. The center of the magnetic pulse cutting coil 30 is kept flush with the end face of the welding wire 20.

[0021] Due to the design of the magnetic pulse cutting coil, and the fact that the center of the magnetic pulse cutting coil is kept flush with the end face of the welding wire, when a pulse current is passed through the magnetic pulse cutting coil, the pulse magnetic field generated therein directly acts on the pulse droplet connection or liquid bridge, thereby achieving precise control of the droplet size and rapid separation, and improving the transition speed.

[0022] The cutting process during the corresponding stages of droplet growth includes: During the EP phase, when the current and voltage of each sub-cycle of the pulsed current are at their peak, the pulsed magnetic field cuts the molten droplet; during the EN phase, when the short-circuit duration reaches a preset threshold, the pulsed magnetic field cuts the liquid bridge.

[0023] To understand the cutting mechanism at this stage, it is necessary to explain the droplet growth stage in the arc-DED process: First, an electric arc ignites at the tip of the welding wire, rapidly heating and melting the wire as a concentrated heat source. The molten metal gathers at the tip of the wire, and due to surface tension, it automatically contracts into a spherical droplet, hanging from the tip; this is the initial forming stage.

[0024] As the welding wire continues to be fed and melted, the molten droplets grow larger and larger, increasing in mass and volume; this is the growth and necking stage.

[0025] Before the molten droplet grows larger, its lower part contacts the molten pool, forming a small bridge of liquid metal. The electric arc is extinguished instantly, and the current conducts through the bridge. Surface tension and electromagnetic contraction force quickly break the small bridge of liquid metal, and the molten droplet is pulled into the molten pool. Afterward, the electric arc reignites. This is the short-circuit transition stage.

[0026] Finally, the molten droplet detaches from the welding wire and falls into the molten pool.

[0027] When a pulsed current is passed through the magnetic pulse cutting coil 30, a pulsed magnetic field is generated near the nozzle 11. The pulsed current includes the EP stage when the sub-circuit current and voltage are at their peak and the corresponding EN stage. The EP stage is the positive polarity stage, and the EN stage is the negative polarity stage. By controlling the pulsed magnetic field, the EP stage of the pulsed current corresponds to the growth and necking stage of the molten droplet, at which time the pulsed magnetic field cuts the molten droplet. The EN stage corresponds to the short-circuit transition stage of the molten droplet, at which time the pulsed magnetic field cuts the liquid bridge, thereby shortening the short-circuit time and reducing the impact of heat input on the molten pool.

[0028] To facilitate understanding of this method, it is explained in detail below, including the following steps: S1. A magnetic pulse cutting coil 30 is installed outside the nozzle 11 of the welding torch 10.

[0029] like Figure 1 As shown, the additive manufacturing equipment includes a welding torch 10 and a magnetic pulse cutting coil 30. The welding torch 10 is fixed to the end of the actuator. It can be understood that the actuator mentioned in this application includes the actuator end of a welding device or the arm of a welding robot. The movement of the actuator drives the movement of the welding torch. Preferably, the welding torch used in this embodiment is a CMT welding torch.

[0030] The nozzle 11 of the welding torch 10 is perpendicular to the end of the welding wire 20. Depending on the actual application scenario, the unmelted portion of the welding wire 20 extending from the end of the nozzle 11 to the surface of the workpiece is generally 12-16 mm. The magnetic pulse cutting coil 30 is installed on both sides of the nozzle 11 of the welding torch 10, and the center of the magnetic pulse cutting coil 30 is kept flush with the end face of the welding wire 20. The welding wire 20 is located above the substrate 40, on which the workpiece 50 is placed.

[0031] In a preferred embodiment of this application, the welding wire material is selected as Al-Zn-Mg-Cu series high-strength aluminum alloy welding wire with a diameter of 0.8~1.6mm.

[0032] Among them, Al-Zn-Mg-Cu series high-strength aluminum alloys have extremely high specific strength and excellent corrosion resistance and heat treatment response performance. They have significant application advantages over traditional aluminum alloys in aerospace, transportation and high-end electronic product appearance parts and support structures, and are particularly suitable for the application scenarios of the embodiments of this application.

[0033] Correspondingly, the substrate is preferably a pure aluminum plate with a thickness of 5 to 20 mm.

[0034] Before the arc additive manufacturing process, the welding wire 20 and the substrate 40 are pretreated. The pretreatment includes removing the oxide film, oil and impurities on the surface of the substrate 40 by mechanical grinding and / or chemical cleaning. The welding wire 20 and the substrate 40 are placed in an oven for heat preservation at a temperature of 80±5℃ for a duration of not less than 6 hours.

[0035] Since the surfaces of welding wire 20 and substrate 40 are not absolutely clean, they may absorb moisture from the air and be contaminated with hydrogen-containing organic matter such as grease. Under the high temperature of the electric arc, the moisture decomposes, and a large amount of atomic hydrogen (H) dissolves in the high-temperature molten pool. As the molten pool rapidly cools and solidifies, the solubility of hydrogen decreases sharply, and the supersaturated hydrogen will precipitate and combine to form hydrogen molecules (H2), forming pores. In addition, a temperature of around 80°C is sufficient to effectively remove most of the water molecule layer adsorbed by physical means without negatively affecting the coating of the welding wire or the performance of the substrate. The dry surfaces of welding wire 20 and substrate 40 can make the arc combustion more stable.

[0036] S2. Perform arc additive manufacturing according to the set process parameters, feed the welding wire 20 to the designated position of the workpiece 50 on the substrate 40 and start the arc to form a molten pool. At the same time, pass a pulse current to the magnetic pulse cutting coil 30 to form a pulse magnetic field, and cut the molten droplet or liquid bridge at the corresponding stage of droplet growth.

[0037] In the embodiments of this application, the process parameters of the electric arc additive manufacturing include, but are not limited to, the travel speed of the electric arc heat source, the wire feeding speed of the welding wire, the purity of the shielding gas, and also include the voltage, current, duration and delay time of the pulse current passed into the magnetic pulse cutting coil.

[0038] The arc heat source travel speed refers to the speed at which the welding torch moves relative to the workpiece, usually measured in mm / s or m / min. It directly affects the geometry and heat input of a single weld pass. With a constant wire feed speed, a faster travel speed results in less metal deposited at the same location per unit time, thus making the single weld pass narrower and thinner. Furthermore, according to... Q=(η*U*I) / V(1) In the formula, η is the thermal efficiency coefficient, U is the arc voltage, and I is the arc current. It can be seen that the travel speed V of the arc heat source is inversely proportional to the heat input Q.

[0039] The wire feed rate refers to the length of the welding wire fed into the molten pool per unit time, usually measured in m / min or mm / s. It directly determines the deposition rate; the faster the feed rate, the more metal is deposited onto the workpiece per unit time, making it the most important parameter affecting manufacturing efficiency. Secondly, increasing the wire feed rate requires a corresponding increase in current from the welding power source to maintain arc stability. This increased current, in turn, leads to increased arc heat and changes in droplet transfer force, thereby altering the weld penetration and width.

[0040] The purity of the protective gas and the content of its effective components (such as Ar) play a crucial role in preventing contamination of the molten pool. High temperatures entering the molten pool are extremely sensitive to impurities in the protective gas (such as oxygen and nitrogen). Insufficient purity of the gas can cause the molten pool to react chemically with the air. In addition, the purity of the protective gas can significantly affect the arc characteristics and droplet transfer, directly altering the arc's shape, stability, and thermal efficiency, thereby affecting the final microstructure and properties of the formed product.

[0041] In the embodiments of this application, the process parameters also include the voltage, current, duration, and delay time of the pulse current supplied to the magnetic pulse cutting coil. The voltage and current of the pulse current directly determine the strength of the pulse magnetic field, and the duration determines the time for the pulse magnetic field to act on the droplet. It is understood that in the embodiments of this application, the duration needs to match the growth frequency of the droplet. The delay time determines which stage of the droplet growth the magnetic force of the pulse magnetic field acts on. It is understood that the delay time needs to be synchronized with the dynamic growth process of the droplet in real time.

[0042] S3. Move the welding wire 20 along the specified path to perform arc additive manufacturing. During this process, adjust the magnetic pulse cutting coil 30 in real time to ensure that the center of the magnetic pulse cutting coil 30 remains flush with the end face of the welding wire 20.

[0043] Due to the design of the magnetic pulse cutting coil 30, and the fact that the center of the magnetic pulse cutting coil 30 is kept flush with the end face of the welding wire 20, when a pulse current is passed through the magnetic pulse cutting coil 30, the pulse magnetic field generated by it can directly act on the pulse droplet connection or liquid bridge, so as to achieve precise control of droplet size and rapid separation, and improve the transition speed. Moreover, the pulse magnetic field can also compress the arc instantaneously before the droplet transition, so that the arc column shrinks and the energy density increases, while reducing the lateral oscillation of the arc, increasing the local heating concentration, reducing spatter and porosity, thereby improving the surface finish and dimensional accuracy of the formed surface. More preferably, an arc compression coil (not shown in the figure) can be provided on the outside of the nozzle 11 of the welding torch 10. During the arc additive manufacturing process, a stable voltage DC current is passed into the arc compression coil. By passing a stable voltage DC current into the arc compression coil, a low amplitude DC magnetic field can be generated to compress the arc, thereby reducing the lateral oscillation of the arc, improving energy concentration, and further reducing the impact of external interference on the forming accuracy.

[0044] In the embodiments of this application, the magnetic pulse cutting coil 30 uses an independent control module to monitor the current-voltage dynamic curve of the pulse current in real time and to perform pulse magnetic field cutting of the molten droplet at regular intervals. This control module is independent of the control module of the electric arc heat source, ensuring accurate and efficient regulation of the pulse magnetic field.

[0045] In the embodiments of this application, the molten droplets deposited on the substrate are subject to an interlayer temperature of 100±20℃, or an interlayer interval waiting time of 2-4 minutes, or rapid cooling of the lower layer before deposition of the upper layer. During the process, if the upper layer temperature is superimposed when the current layer is still in a high-temperature red-hot state, the overall temperature of the workpiece will continue to rise, resulting in heat accumulation and a decrease in workpiece quality. This application achieves temperature regulation between adjacent layers by controlling the interlayer temperature, the interlayer interval waiting time, or the intervention of lower layer cooling to prevent heat accumulation.

[0046] The following describes several specific embodiments of this application: Example 1 High-strength aluminum alloy welding wire of 7075Al-Zn-Mg-Cu series with a diameter of 0.8mm was selected, and the substrate was 7075 aluminum alloy plate with a thickness of 8mm. The welding wire and the substrate were kept in an 80℃ oven for 6 hours before use.

[0047] The process parameters are set as follows: The travel speed of the electric arc heat source is 0.8 m / min.

[0048] Wire feeding speed: 12m / min.

[0049] Protective gas: 99.999% high-purity argon gas, flow rate 18L / min.

[0050] A magnetic pulse cutting coil with an effective core length of 30mm and 30 turns is used, wherein the maximum excitation current of the pulse current is 0.5A, the duration is 0.5ms, and the delay is ≤0.08ms.

[0051] Start arc additive manufacturing: feed the welding wire 20 to the designated position of the workpiece 50 on the substrate 40 and ignite the arc to form a molten pool. Make the welding wire 20 move along the designated path to perform arc additive manufacturing. At the same time, pulse current is passed to the magnetic pulse cutting coil 30 to form a pulse magnetic field. Cut the molten droplet or liquid bridge at the corresponding stage of droplet growth. During this process, adjust the magnetic pulse cutting coil 30 in real time to ensure that the center of the magnetic pulse cutting coil 30 remains flush with the end face of the welding wire 20.

[0052] Forming effect: The deposition efficiency is about 4.5 kg / h, the droplet diameter is stable at 0.6 mm; the surface roughness of the formed part Ra≈4.5 μm, which is about 40% higher than the traditional process; the porosity is 0.10%; the microstructure is mainly composed of fine equiaxed crystals; and the width of the heat-affected zone is significantly reduced.

[0053] Example 2 High-strength aluminum alloy welding wire of 7075Al-Zn-Mg-Cu series with a diameter of 1.6mm was selected, and the substrate was a 7075 aluminum alloy plate with a thickness of 10mm. Preheating and cleaning were the same as in Example 1.

[0054] The process parameters are set as follows: The travel speed of the electric arc heat source is 0.6 m / min.

[0055] Wire feeding speed: 12m / min.

[0056] Protective gas: 99.999% high-purity argon gas, flow rate 18L / min.

[0057] A magnetic pulse cutting coil with an effective core length of 30mm and 30 turns is used, wherein the maximum excitation current of the pulse current is 0.5A, the duration is 0.5ms, and the delay is ≤0.08ms.

[0058] The electric arc additive manufacturing process begins, which is the same as in Example 1 and will not be described again.

[0059] Forming effect: The deposition efficiency is about 5.2 kg / h, the droplet diameter is stable at 0.8 mm; the surface roughness of the formed part Ra≈7.8 μm, the dimensional accuracy is improved by about 32% compared with the traditional process, the porosity is 0.12%, the microstructure is mainly composed of fine equiaxed crystals, and the width of the heat-affected zone is significantly reduced.

[0060] Example 3 7055 aluminum alloy welding wire with a diameter of 1.0 mm was selected, with 3.5 wt.% micron-sized TiB2 particles evenly distributed inside; the substrate was a 7055 aluminum alloy plate with a thickness of 8 mm, and the preheating and cleaning were the same as in Example 1.

[0061] The process parameters are set as follows: The travel speed of the electric arc heat source is 0.5 m / min.

[0062] Wire feeding speed: 10m / min.

[0063] Protective gas: 99.99% pure high-purity argon gas, flow rate 15L / min.

[0064] A magnetic pulse cutting coil with an effective core length of 30mm and 30 turns is used, wherein the maximum excitation current of the pulse current is 0.5A, the duration is 0.4ms, and the delay is ≤0.05ms.

[0065] The electric arc additive manufacturing process begins, which is the same as in Example 1 and will not be described again.

[0066] Forming effect: deposition efficiency is about 4.8 kg / h, droplet diameter is stable at 0.7 mm; surface roughness Ra≈6.9 μm, dimensional accuracy is improved by about 35%, porosity is 0.08%; microstructure is significantly refined, hardness is 10 higher than that of 7075 alloy deposited parts, and corrosion resistance is enhanced.

[0067] Example 4 Al-5Mg welding wire with a diameter of 1.6 mm was selected, and the substrate was a 6 mm thick 5052 aluminum alloy plate. The preheating and cleaning were the same as in Example 1.

[0068] The process parameters are set as follows: The travel speed of the electric arc heat source is 0.9 m / min.

[0069] Wire feeding speed: 20m / min.

[0070] Protective gas: 99.99% pure high-purity argon gas, flow rate 20L / min.

[0071] A magnetic pulse cutting coil with an effective core length of 30mm and 30 turns is used, wherein the maximum excitation current of the pulse current is 0.5A, the duration is 0.3ms, and the delay is ≤0.1ms.

[0072] The electric arc additive manufacturing process begins, which is the same as in Example 1 and will not be described again.

[0073] Forming effect: deposition efficiency is about 6.5 kg / h, droplet diameter is controlled between 0.8 and 1.1 mm; surface roughness Ra≈9.2 μm, dimensional accuracy is improved by about 25%, porosity is 0.15%; the deposited structure is mainly equiaxed crystals with high elongation, which is suitable for manufacturing structural parts that can withstand cyclic loads.

[0074] Example 5 Al-4Cu welding wire with a diameter of 1.2 mm was selected, and the substrate was a 10 mm thick 2219 aluminum alloy plate. Preheating and cleaning were the same as in Example 1.

[0075] The process parameters are set as follows: The travel speed of the electric arc heat source is 0.4 m / min.

[0076] Wire feeding speed: 8m / min.

[0077] Protective gas: 99.99% pure high-purity argon gas, flow rate 20L / min.

[0078] A magnetic pulse cutting coil with an effective core length of 30mm and 30 turns is used, wherein the maximum excitation current of the pulse current is 0.5A, the duration is 0.6ms, and the delay is ≤0.08ms.

[0079] The electric arc additive manufacturing process begins, which is the same as in Example 1 and will not be described again.

[0080] Forming effect: deposition efficiency is about 6.5 kg / h, droplet diameter is controlled between 0.8 and 1.1 mm; surface roughness Ra≈9.2 μm, dimensional accuracy is improved by about 25%, porosity is 0.15%; the deposited structure is mainly equiaxed crystals with high elongation, which is suitable for manufacturing structural parts that can withstand cyclic loads.

[0081] The aforementioned arc additive manufacturing implementation scheme achieves a deposition efficiency of over 4.5 kg / h while improving dimensional accuracy and porosity. The deposition efficiency of arc additive manufacturing is characterized by the amount of raw material deposited per unit time. This parameter reflects the coordination between energy input and material utilization; its improvement signifies achieving a high deposition rate and rapid prototyping effect, making it a core indicator for evaluating process performance. In summary, this invention effectively reduces the impact of molten droplets on the molten pool and heat input by directly applying a pulsed magnetic field to molten droplets or liquid bridges, thereby reducing spatter and porosity formation and suppressing microstructure coarsening. While ensuring a high deposition rate, it achieves ultra-precision forming. It can significantly improve the surface quality and microstructure uniformity of thin-walled, small-sized, and complex structural parts while maintaining the high efficiency of arc-DED, extending the service life of electronic products and expanding the application scope of arc-DED in high-end manufacturing.

[0082] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0083] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0085] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0086] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets, characterized in that, Specifically, the method involves setting a magnetic pulse cutting coil (30) outside the nozzle (11) of the welding torch (10), and passing a pulse current into the magnetic pulse cutting coil (30) during the arc additive manufacturing process to form a pulse magnetic field. The pulse magnetic field is used to cut the molten droplet or liquid bridge at the corresponding stage of the droplet growth. The center of the magnetic pulse cutting coil (30) is kept flush with the end face of the welding wire (20). The pulse current includes the EP phase and the corresponding EN phase when the sub-circuit current and voltage are at their peak. The EP phase is the positive polarity phase, and the EN phase is the negative polarity phase. The cutting of the molten droplet or liquid bridge at the corresponding stage of droplet growth includes: During the EP phase, when the current and voltage of each sub-cycle of the pulsed current are at their peak, the pulsed magnetic field cuts the molten droplet; during the EN phase, when the short-circuit duration reaches a preset threshold, the pulsed magnetic field cuts the liquid bridge.

2. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 1, characterized in that, Includes the following steps: S1. A magnetic pulse cutting coil (30) is set outside the nozzle (11) of the welding torch (10). S2. Perform arc additive manufacturing according to the set process parameters, feed the welding wire (20) to the designated position of the workpiece (50) on the substrate (40) and start the arc to form a molten pool, and at the same time pass the pulse current into the magnetic pulse cutting coil (30) to form a pulse magnetic field, and cut the molten drop or liquid bridge at the corresponding stage of the droplet growth. S3. Move the welding wire (20) along the specified path to perform arc additive manufacturing, and adjust the magnetic pulse cutting coil (30) in real time during the process to ensure that the center of the magnetic pulse cutting coil (30) remains flush with the end face of the welding wire (20).

3. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 2, characterized in that, The welding wire (20) includes a high-strength aluminum alloy welding wire (20) of Al-Zn-Mg-Cu system with a diameter of 0.8~1.6 mm, and the substrate (40) includes a pure aluminum plate with a thickness of 5~20 mm.

4. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 2, characterized in that, Before the arc additive manufacturing process, the welding wire (20) and the substrate (40) are pretreated. The pretreatment includes removing the oxide film, oil and impurities on the surface of the substrate (40) by mechanical grinding and / or chemical cleaning. The welding wire (20) and the substrate (40) are placed in an oven for heat preservation. The oven temperature is 80±5℃ and the heat preservation time is not less than 6 hours.

5. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 2, characterized in that, The process parameters include the travel speed of the electric arc heat source, the wire feeding speed of the welding wire (20), the purity of the shielding gas, and also the maximum excitation current, duration and delay time of the magnetic pulse cutting coil (30).

6. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 1, characterized in that, The magnetic pulse cutting coil (30) uses an independent control module to monitor the current-voltage dynamic curve of the pulse current in real time and to perform pulse magnetic field cutting of the molten droplet at regular intervals.

7. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 1, characterized in that, It also includes setting an arc compression coil outside the nozzle (11) of the welding torch (10) and passing a stable voltage DC current into the arc compression coil during the arc additive manufacturing process.

8. The high deposition rate additive manufacturing method for magnetic pulse cutting of molten droplets according to claim 2, characterized in that, For the molten droplets deposited on the substrate (40), the interlayer temperature is 100±20℃, or the interlayer interval waiting time is 2-4 min, or the next layer is rapidly cooled before the previous layer is deposited.

Images