A smart additive manufacturing method for fabricating helical antenna brackets based on pulsed / continuous lasers

Abstract

This invention belongs to the field of metal additive manufacturing technology, specifically relating to an integrated, high-performance direct forming method for helical antenna metal support structures in communication and navigation equipment. Starting with the pretreatment of the substrate and powder, this invention utilizes a system based on Q-switching of a quasi-continuous-wave laser to achieve pulsed / continuous laser switching, combining continuous laser main forming with pulsed laser auxiliary control. Through precise timing and energy coordination, the process simultaneously optimizes microstructure, controls defects, and optimizes stress during forming, ultimately directly obtaining a high-quality helical antenna support without relying on post-heat treatment to adjust performance. This invention features a simple and controllable process, yields products with excellent performance, and is suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing technology, specifically relating to an integrated, high-performance direct forming method for helical antenna metal support structures in communication and navigation equipment. This method, through the synergistic effect and intelligent control of continuous and pulsed lasers, aims to directly form helical antenna supports with excellent microstructure, high dimensional accuracy, and low internal stress, eliminating the need for subsequent complex heat treatment processes and meeting the application requirements of lightweight and high reliability. Background Technology

[0002] Spiral antennas, with their excellent circular polarization characteristics, wide beam coverage, and compact structure, play an irreplaceable role in satellite navigation, mobile communications, and other fields. Currently, some researchers have attempted to use 3D printing technology to achieve integrated, lightweight manufacturing of four-arm spiral antennas. However, the electrical performance of such antennas (such as axial ratio and phase center stability) is highly dependent on the precision and consistency of their physical structure, among which the manufacturing quality of the metal spiral support, a key load-bearing and positioning component, is crucial.

[0003] Currently, laser powder bed melting technology is an ideal choice for manufacturing such complex metal structures. However, the inherent geometric characteristics of helical supports, such as three-dimensional spatial torsion, large overhang angles, and continuous variable curvature, pose significant challenges to the additive manufacturing process. First, during traditional single-laser scanning, the temperature field distribution in the molten pool is uneven, and the heat flow direction changes drastically with the helical direction. This easily leads to the formation of coarse columnar crystal structures within titanium and aluminum alloys, resulting in significant anisotropy in mechanical properties and affecting the fatigue life of the support as a load-bearing component. Second, in the overhang region, the molten pool lacks solid support below, resulting in poor stability and making it prone to collapse and powder adhesion, leading to surface roughness, dimensional deviations, and internal voids. Furthermore, the residual stress accumulated from complex thermal cycles may cause warping deformation of the component, directly affecting the antenna assembly accuracy and final electrical performance.

[0004] To improve the quality of additively manufactured components, existing technologies have explored methods for introducing auxiliary energy fields. Related patents (such as CN 120961946 A) disclose a method that uses pulsed lasers to control molten pool flow combined with ultrasonic vibration and interlayer remelting, aiming to optimize molten pool behavior and interlayer bonding. Another patent (CN 119182042 B) relates to a laser capable of outputting composite pulses, adjusting the laser output mode by controlling the timing. However, these technologies either focus on the physical control of the molten pool for general structures or emphasize the laser source itself, and have not yet proposed a systematic in-situ solution for the specific component challenge of "spiral antenna supports"—that is, how to simultaneously achieve microstructure refinement, defect suppression, stress control, and dimensional assurance during its complex geometric forming process. In particular, there is a lack of an integrated, supportless manufacturing method that can dynamically adjust auxiliary process parameters according to the geometric characteristics of the spiral structure, thereby achieving integrated "forming-control" and directly obtaining usable components. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an additive manufacturing method for fabricating helical antenna supports based on pulsed / continuous lasers. This method begins with the pretreatment of the substrate and powder, and utilizes a system that achieves pulsed / continuous laser switching based on Q-switching of a quasi-continuous wave laser to perform continuous laser main forming and pulsed laser auxiliary control. Through precise timing and energy coordination, the process is optimized, defect control is achieved, and stress optimization is completed simultaneously during the forming process, ultimately directly obtaining a high-quality helical antenna support without relying on post-heat treatment to adjust performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser, characterized in that the 3D printing includes the following steps:

[0008] S1. Substrate and Powder Pretreatment

[0009] Select a metal substrate and spherical metal powder that are the same material as the target component; perform surface cleaning, planing and preheating on the substrate; perform vacuum drying on the metal powder to remove adsorbed moisture and gas and ensure powder flowability.

[0010] S2. Gas protection

[0011] The pretreated substrate is fixed on the worktable inside the forming cavity; the dried metal powder is evenly spread on the substrate surface using a powder spreading device, with a powder spreading thickness of 20-50 μm and a powder spreading speed of 5-15 mm / s; during the powder spreading and all subsequent processes, a high-purity inert protective gas (such as argon) is continuously introduced into the forming cavity at a flow rate of 10-20 L / min to maintain the oxygen content in the cavity below 100 ppm.

[0012] S3. Pulsed / continuous laser collaborative intelligent additive manufacturing:

[0013] A quasi-continuous wave laser (QCW laser) is used, and the controllable switching between pulsed and continuous lasers is achieved by adjusting its pulse pitch and pulse time. The continuous laser is the main heat source, responsible for melting the powder to form the main molten pool. The pulsed laser is used as the control source, and its output ultrashort pulses have a pulse pitch of 50-120 μm and a pulse time of 60-90 μs. It is used to periodically impact the molten pool. The coordinated movement of the laser's output timing, energy, and scanning speed is controlled. During printing, the continuous laser and the pulsed laser output energy according to the set program.

[0014] The additive manufacturing includes:

[0015] The metal powder is subjected to pulsed laser scanning processing with a pulsed laser power of 200-300 W, a pulse pitch of 50-120 μm, and a pulse duration of 60-90 μs as the base values, while the metal powder is subjected to ultrasonic vibration processing at a frequency of 50-70 kHz.

[0016] After completing single-layer printing, the pulsed laser parameters are adjusted to a high-frequency, low-energy state (70-90 kHz) to perform a rapid remelting of the surface. The scanning path intersects the previous layer's path at a 90° angle, and the remelting depth is controlled at 5-10 μm. Based on the slice data of the helical scaffold's 3D model, the pulsed laser parameters and geometric features (local curvature K, surface normal angle) are established. Mapping relationship:

[0017] For large-angle overhang areas (normal angle) >45°):

[0018] Increase the repetition frequency of the pulsed laser (to 1.0-1.5 times the base value). The high-frequency pulse induces a high-density photoelectric shock wave on the surface of the molten pool, significantly increasing the viscosity of the melt and suppressing the molten pool from falling due to gravity, thereby achieving high-precision forming without physical support.

[0019] For areas with high curvature and corners (such as the bends of spiral arms):

[0020] Increase the energy of a single pulse point. Heat tends to accumulate at corners, leading to coarse grains. The delayed high-energy pulse shock wave can powerfully break up the primary dendrites that grow due to heat accumulation, forming a large number of fragments as heterogeneous nucleation points, forcing columnar crystals to transform into fine equiaxed crystals, fundamentally blocking the propagation path of hot cracks.

[0021] For AlSi10Mg alloys, the standard power of the continuous laser is 300 W and the standard scanning speed is 800-1000 mm / s.

[0022] After completing the current layer, the worktable descends by one layer thickness, and the powder spreading process in step 2 and the pulse / continuous laser co-addition process in step 3 are repeated, layer by layer, until the component is formed.

[0023] The spherical metal powder selected is AiSi10Mg, whose composition, by mass percentage, includes: 10% Si, 0.5% Mg, and the balance being Al.

[0024] After molding, the part is cooled to room temperature under a protective atmosphere, removed, and separated from the substrate. The helical antenna support obtained through this process has a uniform and refined internal structure, few defects, low residual stress, and high dimensional accuracy. It can be used directly for subsequent assembly without the need for special post-heat treatment aimed at improving the structure or eliminating stress.

[0025] This invention maintains coordinated process parameters of 200 W-300 W pulsed laser, 50-120 μm pulse pitch, and 60-90 μs pulse duration. The core principle lies in balancing grain refinement efficiency with molten pool stability. Setting the energy density within this range is sufficient to induce a "photo-induced shock wave" to penetrate the molten pool and break up coarse dendrites, achieving grain refinement, while avoiding excessive energy that could lead to violent metal vaporization and spattering or keyhole porosity. This frequency range ensures that the shock wave continuously covers the scanning path, while preventing heat accumulation due to excessive frequency that would reduce the grain refinement effect. This results in high-quality forming within a stable flow field constructed by continuous laser.

[0026] Select AiSi10Mg spherical powder as the printing alloy powder.

[0027] A preset longitudinal laser scanning path is used to perform pulsed laser scanning on the metal powder with a 250 W pulsed laser, an 80 μm pulse pitch, and a 70 μs pulse duration; the basic parameters of the continuous laser are: power 300 W and scanning speed 1000 mm / s.

[0028] After the single-layer additive manufacturing is completed and naturally cooled to below 150°C, a preset transverse laser scanning path is used, with the scanning range consistent with the additive manufacturing range and a scanning interval of 0.15 mm. The frequency of the pulsed laser generator is adjusted to 80 kHz to remelt the single-layer surface, with a melting thickness of 8 μm. After completion, the surface is cooled for 10 min.

[0029] The bottom bonding area is manufactured, which extends from the substrate along the set printing height direction to 30% of the total height; the continuous laser operates at 75% of the standard power; the pulsed laser operates with a pulse energy of 120 μm pulse pitch and 90 μs pulse duration to sufficiently disturb the initial molten pool and suppress columnar crystal epitaxial growth; based on this, the following parameters are adjusted according to the geometric characteristics of the bottom bonding area:

[0030] For the root chamfer or rounded corner area (where the normal angle changes rapidly): At this time, the heat dissipation volume changes drastically, so the pulsed laser power needs to be reduced to 200 W, while the pulse pitch is slightly reduced to 70~100 μm and the pulse time is reduced to 75~85 μs.

[0031] For the solid support area at the bottom: When scanning the large flat cross section at the bottom, the system maintains standard parameters and uses stable shock waves to induce densification at the bottom, providing a solid, non-porous base for the upper spiral structure.

[0032] The middle main body forming area is manufactured, and the middle main body is directly connected to the bottom joint area. Its area is from the top surface of the bottom joint area along the set printing height direction to 80% of the total height, that is, it is located in the position of 30%-80% of the height range of the entire printed part.

[0033] Continuous laser recovery to 100% standard power (300 W) operation. Based on geometric data of the slice model (surface normal angle). With local curvature K), the driving pulsed laser enters the modulation state:

[0034] Based on the overhang angle (normal angle) The frequency dynamic response. When the scan point is located outside the spiral arm and the surface normal angle is detected. When the angle is greater than 45° (i.e., the large-angle overhang region), the system operates based on the linear mapping relationship between angle and frequency:

[0035] f(θ) = f base + k(θ - 45°),

[0036] Where θ: the currently detected surface normal angle, f base : System fundamental pulse repetition frequency; k: linear growth rate of frequency with increasing angle, i.e., slope;

[0037] Increase the pulsed laser frequency from the base value to 70-80 kHz, while keeping the pulse energy constant.

[0038] Based on the energy variation of local curvature (curvature K), when the scanning point is located at the sharp turn or edge of the spiral arm (high curvature region), the pulsed laser power is increased to 300 W, the pulse time is increased to 60~70 μs, and the pulse triggering sequence is finely controlled to make it lag behind the continuous laser.

[0039] The top finishing area manufacturing (height 80%-100%) is directly connected to the middle body, and its area is from the top surface of the middle body along the set printing height direction to 100% of the total height, that is, it is located in the range of 80%-100% of the total height of the printed part.

[0040] This stage focuses on completing the structure and optimizing the top surface. A "surface finishing mode" is adopted: the continuous laser power is slightly increased to 105% of the nominal value in order to obtain a smoother top surface morphology; the average power and frequency of the pulsed laser are gradually reduced to about 50% of the initial value, mainly for perturbation and homogenization.

[0041] When the laser scan approaches the top tip of the helical antenna or the extremely narrow termination edge (with extremely high curvature), the pulse pitch is attenuated to 50-80 μm and the pulse time is reduced to 60-75 μs.

[0042] To address the unique structure of the helical support, this invention establishes a regionalized control strategy: In the large-angle suspension zone, increasing the pulse frequency generates a high-frequency "photo-tamping" effect, increasing melt viscosity and resisting gravity, effectively solving the collapse and slag accumulation problems in unsupported areas; in the high-curvature corner zone, enhancing pulse energy and delaying triggering precisely impacts the "pasty zone" at the solidification front, forcefully breaking up coarse grains formed by thermal accumulation and cutting off the path of hot crack propagation. This targeted control eliminates structurally specific defects, ensuring the geometric accuracy and mechanical property consistency of complex components.

[0043] Compared with existing methods, the advantages of the present invention are:

[0044] By combining pulsed / continuous lasers, the forming and microstructure control were synchronized and integrated, improving the microstructure of the material from the solidification source.

[0045] By adjusting the synergistic effect of pulsed / continuous laser based on the geometric characteristics of the spiral structure, the structural-specific problems such as the difficulty in forming the overhanging region and the concentration of thermal stress are effectively solved.

[0046] Complete pretreatment and process control enable components to achieve good overall performance after molding, avoiding subsequent complicated heat treatment processes that may cause deformation, shortening the production cycle, and improving manufacturing efficiency and consistency.

[0047] This method is particularly suitable for manufacturing precision components with complex spatial geometry, providing a reliable technical solution for the direct forming of products such as high-performance helical antenna supports. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the process flow of the method of the present invention.

[0049] Figure 2 This is a schematic diagram of the pulsed / continuous laser collaborative additive manufacturing system of the present invention.

[0050] Figure 3 This is a printed result of Example 1.

[0051] Figure 4 This is a printed image of the comparison sample 1.

[0052] Figure 5 This is a printed image of Comparative Example 3. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, a detailed description is provided below with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and do not limit the scope of protection of this invention.

[0054] Example 1:

[0055] This embodiment uses the manufacture of an aluminum alloy (AlSi10Mg) helical antenna bracket for L-band communication as an example. The designed L-band communication helical antenna has a helix diameter of 30 mm, a height of 200 mm, an inner and outer helix structure, and an arm thickness of 2 mm. The inner helix structure has an angle of 45° with the horizontal plane, and the outer helix structure has an angle of 35° with the horizontal plane. This example is used to illustrate the specific implementation of the present invention.

[0056] S1. Substrate and powder pretreatment:

[0057] An AlSi10Mg alloy substrate of suitable size was selected. It was placed in an ultrasonic cleaner containing analytical grade anhydrous ethanol and cleaned at 40 kHz for 12 minutes to remove surface oil. After removal, it was dried with dry nitrogen gas, and then the surface of the substrate was uniformly polished with 800-grit sandpaper to achieve a surface roughness Ra ≤ 1.6 μm. The polished substrate was then placed in a vacuum preheating device and heated to a vacuum degree ≤ 5 × 10⁻⁶. -3 Under Pa conditions, preheat to 150°C and hold for 30 min to remove adsorbed gas and reduce thermal stress.

[0058] Spherical AlSi10Mg alloy powder with a particle size distribution of 15-53 μm was selected. The powder was placed in a vacuum drying oven and dried at 80℃ and a vacuum degree ≤50 Pa for 4 hours, and then cooled to room temperature for use, ensuring good powder flowability.

[0059] S2. Gas protection

[0060] The preheated substrate is mounted on the worktable of the forming equipment. After the forming cavity is sealed, the vacuum pump is started to evacuate the vacuum, and then high-purity argon gas with a purity ≥99.999% is introduced to a pressure slightly above atmospheric pressure. This gas is continuously introduced at a flow rate of 15 L / min during the subsequent process, dynamically maintaining the oxygen content below 50 ppm. A precision scraper-type powder spreader is used to uniformly spread the dried alloy powder onto the substrate surface at a speed of 10 mm / s, controlling the thickness of each powder layer to be 30 μm.

[0061] S3. Pulsed / Continuous Laser Additive Manufacturing:

[0062] The equipment is equipped with a quasi-continuous wave laser (QCW laser), which uses Q-switching technology to obtain high-energy short pulses and continuous lasers. The pulsed and continuous lasers can be output coaxially via a polarization optics system. The slicing file of the spiral support and the preset process parameter package (including basic parameters for continuous lasers: power 300 W, scanning speed 1000 mm / s) are imported into the equipment control system.

[0063] A longitudinal laser scanning path is set, and the metal powder is subjected to pulse laser scanning processing with a pulse laser power of 250 W, a pulse pitch of 80 μm, and a pulse time of 70 μs as the base values. At the same time, the metal powder is subjected to ultrasonic vibration processing at a frequency of 60 kHz. The basic parameters of the continuous laser at this time are: power 300 W, scanning speed 1000 mm / s.

[0064] After the single-layer additive manufacturing is completed and naturally cooled to below 150°C, a preset transverse laser scanning path is used, with the scanning range consistent with the additive manufacturing range and a scanning interval of 0.15 mm. The frequency of the pulsed laser generator is adjusted to a high-frequency, low-energy state of 80 kHz to remelt the single-layer surface, with a melting thickness of 8 μm. After completion, the surface is cooled for 10 min. At this time, the basic parameters of the continuous laser are: power 300 W and scanning speed 1000 mm / s.

[0065] Bottom bonding area manufacturing (the bottom bonding area is 30% of the total height of the substrate along the set printing height direction).

[0066] This stage focuses on ensuring metallurgical bonding and establishing a fine-grained foundation. The control system adopts a preset basic mode: the continuous laser operates at 75% of the standard power (300 W); the pulsed laser operates with a pulse energy of 120 μm pulse pitch and 90 μs pulse duration to fully disturb the initial molten pool and suppress columnar crystal epitaxial growth.

[0067] Based on this, the system adjusts the following parameters according to the geometric features of the bottom connection:

[0068] For the root chamfered or rounded corner area (where the normal angle changes rapidly): when the slice outline is detected as a transition rounded corner connecting the spiral support and the substrate, the system identifies a sharp change in heat dissipation volume at that location. The pulsed laser power is reduced to 200W, while the pulse pitch is slightly reduced to 85 μm and the pulse duration to 80 μs.

[0069] For the solid support area at the bottom (curvature K≈0): When scanning the large flat section at the bottom, the system maintains standard parameters and uses stable shock waves to induce densification at the bottom, providing a solid, non-porous base for the upper spiral structure.

[0070] Manufacturing of the middle main body forming area (height 30%-80%, that is, the middle main body and the bottom joint area are directly connected, and its area is from the top surface of the bottom joint area along the set printing height direction to 80% of the total height, that is, it is located at the position of 30%-80% of the height range of the entire printed part).

[0071] This stage, where the main spiral structure is formed, is the most geometrically complex and critically controllable region. Continuous laser power is restored to 100% of the nominal power (300W). The system reads the geometric data of the sliced ​​model (surface normal angle). With local curvature K), and drive the pulsed laser into an active modulation state:

[0072] Based on the overhang angle (normal angle) The frequency dynamic response. When the scan point is located outside the spiral arm and the surface normal angle is detected. When the angle is greater than 45° (i.e., the large-angle overhang region), the system operates based on the linear mapping relationship between angle and frequency:

[0073] f(θ) = f base + k(θ - 45°),

[0074] Where θ: the currently detected surface normal angle, f base : System fundamental pulse repetition frequency; k: linear growth rate of frequency with increasing angle, i.e., slope;

[0075] The pulsed laser frequency was increased from the base value to 75 kHz, while the pulse energy remained unchanged.

[0076] Based on the energy variation of local curvature (curvature K), when the scanning point is located at the sharp turn or edge of the spiral arm (high curvature region), the system increases the pulsed laser power to 300 W and the pulse time to 65 μs.

[0077] Manufacturing of the top finishing area (80%-100% of the height, the top finishing area is directly connected to the middle body, and its area is from the top surface of the middle body along the set printing height direction to 100% of the total height, that is, it is located in the range of 80%-100% of the total height of the printed part).

[0078] This stage focuses on completing the structure and optimizing the top surface. A "surface finishing mode" is adopted: the continuous laser power is slightly increased to 105% of the nominal value in order to obtain a smoother top surface morphology; the average power and frequency of the pulsed laser are gradually reduced to about 50% of the initial value, mainly for perturbation and homogenization.

[0079] When the laser scan approaches the top tip of the helical antenna or the extremely narrow terminating edge (with extremely high curvature), the system reduces the pulse pitch to 70 μm and the pulse duration to 65 μs.

[0080] S4. After all layers have been printed, remove the component and cool it to below 80°C under continuous argon protection. Turn off the atmosphere system, open the molding chamber, and remove the molded substrate.

[0081] The aluminum alloy (AlSi10Mg) helical antenna bracket product for L-band communication manufactured using the above process is shown below. Figure 3 The pre-formed helical antenna support is separated from the substrate using wire cutting. The support obtained directly through this process has no significant coarse columnar crystals, good surface quality, and dimensional accuracy that meets design requirements.

[0082] Example 2

[0083] This embodiment examines the influence of the lower limit edge parameter of the process window on the forming of the spiral support. This embodiment is implemented according to the following steps:

[0084] S1. Substrate and powder pretreatment:

[0085] An AlSi10Mg alloy substrate of suitable size was selected. It was placed in an ultrasonic cleaner containing analytical grade anhydrous ethanol and cleaned at 40 kHz for 12 min to remove surface oil. After removal, it was dried with dry nitrogen gas, and then the surface of the substrate was uniformly polished with 800-grit sandpaper to achieve a surface roughness Ra ≤ 1.6 μm. The polished substrate was then placed in a vacuum preheating device and heated to a vacuum degree ≤ 5 × 10⁻⁶. -3 Under Pa conditions, preheat to 150°C and hold for 30 min to remove adsorbed gas and reduce thermal stress.

[0086] Spherical AlSi10Mg alloy powder with a particle size distribution of 15-53 μm was selected. The powder was placed in a vacuum drying oven and dried at 80℃ and a vacuum degree ≤50 Pa for 4 h, and then cooled to room temperature for use, ensuring good powder flowability.

[0087] S2. Gas protection

[0088] The preheated substrate is mounted on the worktable of the forming equipment. After the forming cavity is sealed, the vacuum pump is started to evacuate the vacuum, and then high-purity argon gas with a purity ≥99.999% is introduced to a pressure slightly above atmospheric pressure. This gas is continuously introduced at a flow rate of 15 L / min during the subsequent process, dynamically maintaining the oxygen content below 50 ppm. A precision scraper-type powder spreader is used to uniformly spread the dried alloy powder onto the substrate surface at a speed of 10 mm / s, controlling the thickness of each powder layer to be 30 μm.

[0089] S3. Pulsed / Continuous Laser Additive Manufacturing:

[0090] The equipment is equipped with a quasi-continuous wave laser (QCW laser), which uses Q-switching technology to obtain high-energy short pulses and continuous lasers. The pulsed and continuous lasers can be output coaxially via a polarization optics system. The slicing file of the spiral support and the preset process parameter package (including basic parameters for continuous lasers: power 300 W, scanning speed 1000 mm / s) are imported into the equipment control system.

[0091] A preset longitudinal laser scanning path is used to perform pulsed laser scanning on the metal powder with a pulsed laser power of 200 W, a pulse pitch of 55 μm, and a pulse duration of 65 μs as the base values. At the same time, the metal powder is subjected to ultrasonic vibration treatment at a frequency of 50 kHz. The basic parameters of the continuous laser at this time are: power 300 W and scanning speed 1000 mm / s.

[0092] After the single-layer additive manufacturing is completed and naturally cooled to below 150°C, a preset transverse laser scanning path is used, with the scanning range consistent with the additive manufacturing range and a scanning interval of 0.15 mm. The frequency of the pulsed laser is adjusted to a high-frequency, low-energy state of 65 kHz to remelt the single-layer surface, with a melting thickness of 8 μm. After completion, the surface is cooled for 10 min.

[0093] Manufacturing of the bottom bonding area (regional division is consistent with Example 1)

[0094] This stage focuses on ensuring metallurgical bonding and establishing a fine-grained foundation. The control system adopts a preset basic mode: the continuous laser operates at 75% of the standard power (300 W); the pulsed laser operates synchronously with a 100 μm pulse pitch and an 80 μs pulse time to fully disturb the initial molten pool and suppress columnar crystal epitaxial growth.

[0095] Based on this, the system adjusts the following parameters according to the geometric features of the bottom connection:

[0096] For the root chamfered or rounded corner area (where the normal angle changes rapidly): when the slice outline is detected as a transition rounded corner connecting the spiral support and the substrate, the system identifies a sharp change in heat dissipation volume at that location. In this case, the pulse pitch is dynamically reduced to 70 μm and the pulse time to 75 μs.

[0097] For the solid support area at the bottom (curvature K≈0): When scanning the large flat section at the bottom, the system maintains standard parameters and uses stable shock waves to induce densification at the bottom, providing a solid, non-porous base for the upper spiral structure.

[0098] Manufacturing of the central main body forming area (regional division is consistent with Example 1)

[0099] Continuous laser power recovery to 100% standard operation. Based on geometric data from the slice model (surface normal angle). With local curvature K), and drive the pulsed laser into an active modulation state:

[0100] Based on the overhang angle (normal angle) The frequency dynamic response. When the scan point is located outside the spiral arm and the surface normal angle is detected. When the angle is greater than 45° (i.e., the large-angle suspension region), the system increases the pulsed laser frequency from the base value to 70 kHz based on the "angle-frequency" linear mapping relationship, while keeping the pulse energy constant.

[0101] Based on the energy variation of local curvature (curvature K), when the scanning point is located at the sharp turn or edge of the spiral arm (high curvature region), the pulsed laser power is increased to 220 W and the pulse time is increased to 60 μs.

[0102] Manufacturing of the top finishing area (the area division is the same as in Example 1)

[0103] This stage focuses on completing the structure and optimizing the top surface. A "surface finishing mode" is adopted: the continuous laser power is slightly increased to 105% of the nominal value in order to obtain a smoother top surface morphology; the average power and frequency of the pulsed laser are gradually reduced to about 50% of the initial value, mainly for perturbation and homogenization.

[0104] When the laser scan approaches the top tip of the helical antenna or the extremely narrow terminating edge (with extremely high curvature), the system reduces the pulse pitch to 50 μm and sets the pulse duration to 60 μs.

[0105] S3. After the component is removed and all layers are printed, it is cooled to below 80°C under continuous argon protection. The atmosphere system is then turned off, the molding chamber is opened, and the molded substrate is removed.

[0106] The spiral support was formed intact without serious collapse. However, slight powder adhesion was visible under a microscope at the edge of the overhanging surface. This was due to the slightly lower energy and insufficient wetting of the unmelted powder by the edge melt.

[0107] Comparative Example 1

[0108] This comparative study examines the effect of single-laser (continuous laser) printing on the formation of a spiral support. This embodiment is implemented according to the following steps:

[0109] S1. Substrate and powder pretreatment:

[0110] An AlSi10Mg alloy substrate of suitable size was selected. It was placed in an ultrasonic cleaner containing analytical grade anhydrous ethanol and cleaned at 40 kHz for 12 min to remove surface oil. After removal, it was dried with dry nitrogen gas, and then the surface of the substrate was uniformly polished with 800-grit sandpaper to achieve a surface roughness Ra ≤ 1.6 μm. The polished substrate was then placed in a vacuum preheating device and preheated to 150℃ under a vacuum degree ≤ 5 × 10⁻³ Pa, and held at that temperature for 30 min to remove adsorbed gases and reduce thermal stress.

[0111] Spherical AlSi10Mg alloy powder with a particle size distribution of 15-53 μm was selected. The powder was placed in a vacuum drying oven and dried at 80℃ and a vacuum degree ≤50 Pa for 4 h, and then cooled to room temperature for use, ensuring good powder flowability.

[0112] S2. Gas protection

[0113] The preheated substrate is mounted on the worktable of the forming equipment. After the forming cavity is sealed, the vacuum pump is started to evacuate the vacuum, and then high-purity argon gas with a purity ≥99.999% is introduced to a pressure slightly above atmospheric pressure. This gas is continuously introduced at a flow rate of 15 L / min during the subsequent process, dynamically maintaining the oxygen content below 50 ppm. A precision scraper-type powder spreader is used to uniformly spread the dried alloy powder onto the substrate surface at a speed of 10 mm / s, controlling the thickness of each powder layer to be 30 μm.

[0114] S3. Single-laser additive manufacturing:

[0115] Q-switched printing uses only a 300 W continuous laser for printing, without interlayer remelting. Printing allowances are set based on the inner and outer spiral structures and the angle between the inner and outer spirals and the horizontal plane. For the outer spiral structure, the printing allowance is set to 2 mm for the wall thickness and 0.2 mm for the allowance. SLM printing is performed using a common parallel grating scanning strategy to obtain the printed part. The laser scans along the contour ring of the cross-section, layer by layer from the outside inwards towards the center. Printing parameters are: layer thickness 0.04 mm, scanning speed 1200 mm / s, scanning spacing 0.08 mm, and laser power 300 W. The scanning speed is 1200 mm / s.

[0116] S4. After all layers have been printed, remove the component and cool it to below 80°C under continuous argon protection. Turn off the atmosphere system, open the molding chamber, and remove the molded substrate.

[0117] See molding effect Figure 4 The hanging surface of the spiral support suffered severe collapse and slag buildup, and the dimensional accuracy could not meet the assembly requirements.

[0118] Comparative Example 2

[0119] This comparative study mainly investigates the regulation without geometric features. The specific implementation steps are as follows:

[0120] S1. Substrate and powder pretreatment:

[0121] An AlSi10Mg alloy substrate of suitable size was selected. It was placed in an ultrasonic cleaner containing analytical grade anhydrous ethanol and cleaned at 40 kHz for 12 min to remove surface oil. After removal, it was dried with dry nitrogen gas, and then the surface of the substrate was uniformly polished with 800-grit sandpaper to achieve a surface roughness Ra ≤ 1.6 μm. The polished substrate was then placed in a vacuum preheating device and heated to a vacuum degree ≤ 5 × 10⁻⁶. -3 Under Pa conditions, preheat to 150°C and hold for 30 min to remove adsorbed gas and reduce thermal stress.

[0122] Spherical AlSi10Mg alloy powder with a particle size distribution of 15-53 μm was selected. The powder was placed in a vacuum drying oven and dried at 80℃ and a vacuum degree ≤50 Pa for 4 h, and then cooled to room temperature for use, ensuring good powder flowability.

[0123] S2. Gas protection

[0124] The preheated substrate is mounted on the worktable of the forming equipment. After the forming cavity is sealed, the vacuum pump is started to evacuate the vacuum, and then high-purity argon gas with a purity ≥99.999% is introduced to a pressure slightly above atmospheric pressure. This gas is continuously introduced at a flow rate of 15 L / min during the subsequent process, dynamically maintaining the oxygen content below 50 ppm. A precision scraper-type powder spreader is used to uniformly spread the dried alloy powder onto the substrate surface at a speed of 10 mm / s, controlling the thickness of each powder layer to be 30 μm.

[0125] S3. Pulsed / Continuous Laser Additive Manufacturing:

[0126] The pulsed / continuous laser system is activated, but the pulse parameters remain constant throughout the process (fixed at 250 W pulsed laser, 80 μm pulse pitch, and 70 μs pulse duration), without adjustment based on changes in the overhang angle and curvature of the helical structure. The continuous laser is kept constant at 300 W, and the scanning speed is 1200 m / s.

[0127] S4. After all layers have been printed, remove the component and cool it to below 80°C under continuous argon protection. Turn off the atmosphere system, open the molding chamber, and remove the molded substrate.

[0128] The obtained sample exhibits a rough lower surface in the overhang region. In the high curvature region, due to the lack of hysteresis-induced thermal depression elimination from strong impacts, metallographic observation revealed minute thermal cracks. Although the density is superior to single-laser processing, defects at complex geometric features lead to a significant decrease in fatigue performance.

[0129] Comparative Example 3

[0130] This embodiment examines the effect of a single laser (pulsed laser) on the forming of a helical support. This embodiment is implemented according to the following steps.

[0131] This comparative study mainly investigates the regulation without geometric features. The specific implementation steps are as follows:

[0132] S1. Substrate and powder pretreatment:

[0133] An AlSi10Mg alloy substrate of suitable size was selected. It was placed in an ultrasonic cleaner containing analytical grade anhydrous ethanol and cleaned at 40 kHz for 12 min to remove surface oil. After removal, it was dried with dry nitrogen gas, and then the surface of the substrate was uniformly polished with 800-grit sandpaper to achieve a surface roughness Ra ≤ 1.6 μm. The polished substrate was then placed in a vacuum preheating device and heated to a vacuum degree ≤ 5 × 10⁻⁶. -3 Under Pa conditions, preheat to 150°C and hold for 30 min to remove adsorbed gas and reduce thermal stress.

[0134] Spherical AlSi10Mg alloy powder with a particle size distribution of 15-53 μm was selected. The powder was placed in a vacuum drying oven and dried at 80℃ and a vacuum degree ≤50 Pa for 4 h, and then cooled to room temperature for use, ensuring good powder flowability.

[0135] S2. Gas protection

[0136] The preheated substrate is mounted on the worktable of the forming equipment. After the forming cavity is sealed, the vacuum pump is started to evacuate the vacuum, and then high-purity argon gas with a purity ≥99.999% is introduced to a pressure slightly above atmospheric pressure. This gas is continuously introduced at a flow rate of 15 L / min during the subsequent process, dynamically maintaining the oxygen content below 50 ppm. A precision scraper-type powder spreader is used to uniformly spread the dried alloy powder onto the substrate surface at a speed of 10 mm / s, controlling the thickness of each powder layer to be 30 μm.

[0137] S3. Single-laser additive manufacturing:

[0138] The equipment is equipped with a quasi-continuous wave laser (QCW laser), Q-switched to pulsed laser mode, eliminating interlayer remelting. The printing allowance is set according to the inner and outer spiral structures and the angle between them and the horizontal plane. For the outer spiral structure, the printing wall thickness is 2 mm, and the printing allowance is 0.2 mm.

[0139] A preset longitudinal laser scanning path is used to perform pulsed laser scanning processing on the metal powder with a pulsed laser power of 250 W, a pulse point spacing of 100 μm, and a pulse duration of 70 μs.

[0140] S3. After the component is removed and all layers are printed, it is cooled to below 80°C under continuous argon protection. The atmosphere system is then turned off, the molding chamber is opened, and the molded substrate is removed.

[0141] See molding effect Figure 5 The spiral support is poorly formed overall, with a high surface roughness. Furthermore, noticeable surface unevenness is visible at the edges of the overhanging surface, indicating poor molding quality.

[0142] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0143] This specific embodiment fully demonstrates that the present invention, through the synergy of three core strategies—pulse / continuous laser precise path control, pulse mode switching based on feature position, and global sequence energy distribution—can precisely control the contradictions of "geometry-thermodynamics-structure" in the additive manufacturing process of helical supports, thereby obtaining high-performance components with excellent microstructure, homogeneous mechanical properties, and precise geometric forming.

Claims

1. An additive manufacturing method for fabricating a helical antenna support based on pulsed / continuous laser, characterized in that: Includes the following steps: S1. Substrate and Powder Pretreatment A metal substrate and spherical metal powder of the same material as the target component are selected; the substrate is surface-cleaned, planarized, and preheated; the metal powder is then vacuum-dried. S2. Gas protection The pretreated substrate is fixed on the worktable inside the forming cavity; the dried metal powder is evenly spread on the substrate surface using a powder spreading device, with a powder spreading thickness of 20-50 μm and a powder spreading speed of 5-15 mm / s; during the powder spreading and all subsequent processes, inert protective gas is continuously introduced into the forming cavity at a flow rate of 10-20 L / min to maintain the oxygen content in the cavity below 100 ppm. S3. Pulsed / Continuous Laser Collaborative Intelligent Additive Manufacturing A quasi-continuous wave laser (QCW laser) is used, and the controllable switching between pulsed and continuous lasers is achieved by adjusting its pulse pitch and pulse time. The continuous laser is the main heat source, responsible for melting the powder to form the main molten pool. The pulsed laser is used as the control source, and its output ultrashort pulses have a pulse pitch of 50-120 μm and a pulse time of 60-90 μs. It is used to periodically impact the molten pool. The coordinated movement of the laser's output timing, energy, and scanning speed is controlled. During printing, the continuous laser and the pulsed laser output energy according to the set program.

2. The additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser according to claim 1, characterized in that: The additive manufacturing includes: The metal powder is subjected to pulsed laser scanning processing with a pulsed laser power of 200-300 W, a pulse pitch of 50-120 μm, and a pulse duration of 60-90 μs as the base values, while the metal powder is subjected to ultrasonic vibration processing at a frequency of 50-70 kHz. After completing single-layer printing, the pulsed laser parameters are adjusted to a high-frequency, low-energy state (70-90 kHz) to perform a rapid remelting of the surface. The scanning path intersects the previous layer's path at a 90° angle, and the remelting depth is controlled at 5-10 μm. Based on the slice data of the helical support 3D model, a mapping relationship between the pulsed laser parameters and geometric features is established: the geometric features are the local curvature K and the surface normal angle. For areas with large-angle overhangs, i.e., normal angles For regions >45°: Increase the repetition rate of the pulsed laser to 1.0-1.5 times the base value; For the turning points of the spiral arm: increase the single-point energy of the pulse.

3. The additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser according to claim 1, characterized in that: For AlSi10Mg alloys, the standard power of the continuous laser is 300 W, and the standard scanning speed is 800-1000 mm / s.

4. The additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser according to claim 1, characterized in that: After completing the current layer, the worktable descends by one layer thickness, and the powder spreading process in step 2 and the pulse / continuous laser co-addition process in step 3 are repeated, layer by layer, until the component is formed.

5. The additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser according to claim 1, characterized in that: The material of the spherical metal powder is selected from AlSi10Mg, and its composition, by mass percentage, includes: 10% Si, 0.5% Mg, and the balance being Al.

6. The additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser according to claim 1, characterized in that: A synergistic window of 200-300 W pulsed laser power, 50-120 μm pulse pitch, and 60-90 μs pulse duration.

7. The additive manufacturing method for fabricating a helical antenna bracket based on pulsed / continuous laser according to claim 1, characterized in that: When the material of the spherical metal powder is AlSi10Mg, A preset longitudinal laser scanning path is used to perform pulsed laser scanning on the metal powder with a 250 W pulsed laser, an 80 μm pulse pitch, and a 70 μs pulse duration; the basic parameters of the continuous laser are: power 300 W and scanning speed 1000 mm / s. After the single-layer additive manufacturing is completed and naturally cooled to below 150°C, a preset transverse laser scanning path is used, with the scanning range consistent with the additive manufacturing range and a scanning interval of 0.15 mm. The frequency of the pulsed laser generator is adjusted to 80 kHz, and the single-layer surface is remelted with a melting thickness of 8 μm. After completion, it is cooled for 10 min. The bottom bonding area is manufactured, which extends from the substrate along the set printing height direction to 30% of the total height; the continuous laser operates at 75% of the standard power of 300 W; the pulsed laser operates with a pulse energy of 120 μm pulse pitch and 90 μs pulse duration to sufficiently disturb the initial molten pool and suppress columnar crystal epitaxial growth; based on this, the following parameters are adjusted according to the geometric characteristics of the bottom bonding area: For root chamfered or rounded corner areas: dynamically reduce pulsed laser power to 200 W, while slightly reducing pulse pitch to 70~100 μm and pulse duration to 75~85 μs; For the solid support area at the bottom: when the bottom is a flat cross section, the system maintains standard parameters and uses stable shock waves to induce densification at the bottom, providing a solid, non-porous base for the upper spiral structure; The central main body forming area is manufactured, and the central main body is directly connected to the bottom bonding area. Its area extends from the top surface of the bottom bonding area along the set printing height direction to 80% of the total height, i.e., it is located at 30%-80% of the total printed part height range. The continuous laser is restored to 100% standard power, i.e., 300 W. Based on the geometric data of the slicing model, the driven pulsed laser enters a controlled state: the geometric data of the slicing model is the surface normal angle. With local curvature K; Based on the overhang angle, i.e., the normal angle The frequency dynamic response; when the scan point is located outside the spiral arm and the surface normal angle is detected. At angles greater than 45°, the system operates based on a linear mapping relationship between angle and frequency: f(θ )= f base + k(θ - 45°), Where θ: the currently detected surface normal angle, f base : System fundamental pulse repetition frequency; k: linear growth rate of frequency with increasing angle, i.e., slope; Increase the pulsed laser frequency from the base value to 70-80 kHz, while keeping the pulse energy constant; When the scanning point is located at the sharp turn or edge of the spiral arm, the pulsed laser power is increased to 300 W, the pulse time is increased to 60~70 μs, and the pulse triggering sequence is finely controlled to make it lag behind the continuous laser. The top finishing area is manufactured and is directly connected to the middle main body. Its area extends from the top surface of the middle main body along the set printing height direction to 100% of the total height, that is, it is located in the range of 80%-100% of the total height of the printed part. The "surface finishing mode" is adopted: the continuous laser power is slightly increased to 105% of the nominal value in order to obtain a smoother upper surface morphology; the average power and frequency of the pulsed laser are gradually reduced to about 50% of the initial value, mainly for perturbation and homogenization; when the laser scan is close to the top tip of the helical antenna or the extremely narrow termination edge, the pulse dot pitch is set to 50-80 μm and the pulse time is 60-75 μs.

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