A method of additive manufacturing by separate melting of coarse and fine powders, a manufactured part, a system and applications

Abstract

The application discloses a kind of coarse and fine powder partition melting additive manufacturing method, article, system and application, the three-dimensional model of the article to be shaped is divided into first, second area by each layer slice forming area, coarse powder is laid in powder bed whole domain, after removing the coarse powder in second area, fine powder is laid in second area, second area is fused layer by layer using small size laser beam, first area is fused using large size laser beam, the forming layer thickness of the first area is k times the forming layer thickness of second area, also construct the control system of powder particle size-beam diameter-forming area-layer thickness and forming timing, and provide the additive manufacturing system suitable for coarse and fine powder partition powder laying and laser partition melting.The application can effectively utilize coarse powder to realize cost reduction and efficiency improvement, while ensuring the forming precision of fine structure, significantly reducing the forming time, further meeting the forming needs of fine inner runner, fine lightweight cell structure, fine microporous structure and other fine structures.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to an additive manufacturing method, part, system and application of partitioned melting of coarse and fine powders. Background Technology

[0002] In recent years, additive manufacturing technology has attracted widespread attention due to its significant advantages in rapidly prototyping complex components. Laser powder bed melting (LPBF), as a core technology of additive manufacturing, has advantages such as high structural design freedom and the ability to manufacture complex structures in an integrated manner. It has shown significant application potential in the manufacturing of complex components in aerospace, automotive, consumer electronics, marine, medical, and mold industries, and has become a key technology for forming core components of high-end equipment.

[0003] Complex components with intricate internal flow channels, lightweight cellular structures, and microporous structures have significant application value in aerospace, automotive, consumer electronics, marine, medical, and mold-making industries. For example, aero-engine fuel nozzles achieve better combustion through intricate internal flow channels and micropores, while aero-engine casings can achieve weight reduction through intricate lightweight cellular structures. The demand for such complex components with intricate structures is increasingly urgent across various fields. These intricate structures require high forming precision and surface quality. Traditional laser powder bed fusion (LPBF) technology typically uses laser beams with diameters of 60–80 μm, limiting forming precision. Furthermore, to ensure forming precision, fine powder is usually used, resulting in thinner layers, which further limits the improvement of overall forming efficiency. Existing LPBF technology is insufficient to meet the further demands of industrial development in various fields.

[0004] Especially for the forming of large-sized (≥200 mm in at least one direction) or even meter-sized (≥1000 mm in at least one direction) components, hundreds of kilograms or even tons of powder are often required, resulting in a very high proportion of powder costs. Further reducing powder usage costs is of great significance for the forming and manufacturing of large-sized components. In particular, when developing new alloys specifically for laser powder bed fusion and forming components, new pre-alloyed powders need to be customized. The cost of these customized powders is usually higher than that of commonly available powders. Moreover, during process testing and component forming, a large amount of powder needs to be spread across the powder bed. When customizing a batch of new alloy powders, in addition to collecting 15~53 μm powder, powders of 0~25 μm, 53~150 μm, and even larger than 150 μm are also produced simultaneously. Currently, the mainstream of existing LPBF technology utilizes 15~53 μm powders, and powders in other particle size ranges are not utilized efficiently, which significantly increases the manufacturing cost of customized alloy components and also restricts the research and application of new alloys in LPBF technology. In recent years, a few patents have proposed recycling methods that use a mixture of coarse and fine powders for coarse powder recycling. While this can reduce costs to some extent, it is difficult to guarantee the precision of the parts, and it will affect the surface and contour quality and precision of the parts.

[0005] In summary, existing LPBF technology faces the dual technical challenges of balancing high-precision forming of fine structures with overall manufacturing efficiency, and high manufacturing costs due to the inefficient utilization of powders of different particle sizes. These challenges have become key bottlenecks restricting its further promotion and application in the industrial manufacturing of high-end complex components. There is an urgent need to propose an LPBF process improvement scheme that can simultaneously achieve high-precision forming of fine structures, improve overall manufacturing efficiency, and efficiently utilize coarse and fine powders. Summary of the Invention

[0006] The purpose of this invention is to provide an additive manufacturing method, part, system and application of partitioned melting of coarse and fine powders, which can realize the graded and regional independent control of powder and laser, effectively utilize coarse powder to reduce costs and increase efficiency, and through the synergistic cooperation of laser and powder, ensure the forming accuracy of fine structure while greatly reducing forming time.

[0007] To achieve the above-mentioned technical effects, the present invention provides an additive manufacturing method for partitioned melting of coarse and fine powders, comprising:

[0008] The 3D model of the part to be formed is sliced ​​into layers to obtain the slicing path of each layer. The forming area in each slice is divided into the first region and the second region. In the process of melting and forming the part to be formed using laser powder bed melting technology, the powder formed in the first region is the first powder, and the powder formed in the second region is the second powder. The average particle size D150 of the first powder is greater than the average particle size D250 of the second powder. D150 and D250 are the particle sizes corresponding to the cumulative distribution ratio of volume fraction in the first powder and the second powder, respectively, reaching 50%. A first laser beam is used to laser scan and shape a first region, and a second laser beam is used to laser scan and shape a second region. The diameter B1 of the first laser beam is greater than the diameter B2 of the second laser beam. The thickness T1 of the shaped layer in the first region is k times the thickness T2 of the shaped layer in the second region, where k is a positive integer and k≥2. The second region uses a layer-by-layer laser melting process to complete the laser melting of each layup, while the first region uses a concentrated laser melting process for the corresponding k layup thicknesses. This process is repeated until the final part is formed.

[0009] In the above scheme, it is readily understood in the art that the thickness of each ply depends on the thickness T2 of the second region forming layer, that is, the thickness of each ply is equal to the thickness T2 of the second region forming layer.

[0010] It should be noted that, in the basic technical solution of this invention, the specific particle size of coarse and fine powders and the diameter of the laser beam are not specifically limited. The core improvement of this invention compared with the prior art is that, unlike the traditional laser powder bed melting process which uses powder of a single particle size, this invention emphasizes the partitioning of coarse and fine powders, and proposes a complete concept of using laser partitions with different beam diameters to match the melting of coarse and fine powders and setting different forming layer thicknesses for coarse and fine powders respectively. In this invention, the average particle size D150 of the first powder is greater than the average particle size D250 of the second powder, and the diameter B1 of the first laser beam is greater than the diameter B2 of the second laser beam. The two powders and two laser beams have relative concepts of coarseness and size; therefore, the first powder is coarse powder, the second powder is fine powder, the first laser beam is a large-size laser beam, and the second laser beam is a small-size laser beam. This allows for the use of fine powder and a small-size laser beam to maintain precision and surface quality in the forming process, while coarse powder and a large-size laser beam are used to maintain efficiency in other structures. This achieves graded and regional coordinated control of the powder and laser, thereby reducing costs and increasing efficiency while ensuring forming accuracy. Any adjustment or change to the specific particle size and laser beam diameter without departing from the spirit of this invention does not deviate from the principles and scope of this invention and should be included within the protection scope of this invention.

[0011] Furthermore, it is particularly important to emphasize that, unlike the single-layer thickness design approach in traditional laser powder bed melting processes, this invention targets the zonal melting characteristics of coarse and fine powders. By linking the layer thickness ratio with the forming sequence, the first region is formed using a low-frequency concentrated melting method, while the second region is formed using a high-frequency layer-by-layer melting method. This significantly reduces the forming time while ensuring the forming accuracy and quality performance requirements of the first and second regions.

[0012] In some embodiments, the first powder is simultaneously laid on the first region and the second region in the first layer of the powder bed; the first powder in the second region of the current layer is removed, the second powder is laid on the second region and leveled, and the second laser beam is used to laser melt and shape the second region, while the first region is not laser melt and shaped temporarily; When k=2, the first powder is simultaneously laid in the first and second regions of the second layer of the powder bed, the first powder in the second region is removed, the second powder is laid in the second region and leveled, the second laser beam is used to perform laser melting and forming on the second region, and the first laser beam is used to perform single-stage concentrated laser melting and forming on the first region. Alternatively, the first powder is simultaneously laid in the first and second regions of the second layer of the powder bed, and the first laser beam is used to perform a single concentrated laser melting and forming on the first region. The first powder in the second region is removed, the second powder is laid and leveled in the second region, and the second laser beam is used to perform laser melting and forming on the second region. This process is repeated until the entire part to be formed is finally completed; When k>2, the first powder is continuously laid on both the first and second regions of the second layer of the powder bed. The first powder in the second region is removed, and the second powder is laid on and leveled in the second region. The second laser beam is used to perform laser melting and forming on the second region. The first region is not laser-melted and formed temporarily. Until the kth layer, the first powder is laid on both the first and second regions simultaneously. The first powder in the second region is removed, and the second powder is laid on and leveled. The first laser beam is used to perform single-stage concentrated laser melting and forming on the first region, and the second laser beam is used to perform laser melting and forming on the second region of the kth layer. Or until the k-th layer is laid, after the first powder is laid on the first region and the second region simultaneously, the first laser beam is used to perform a single concentrated laser melting and forming on the first region, the first powder in the second region is removed, and then the second powder is laid and leveled, and the second laser beam is used to perform laser melting and forming on the second region of the k-th layer. This process is repeated until the entire part to be formed is finally completed.

[0013] In the preferred embodiment of this invention, the powder-laying steps for the partitioning of coarse and fine powders are further refined, which is more conducive to the efficient and high-quality partitioning of coarse and fine powders in the same layer. It should be noted that, in the k-th layer, there is no sequential order between the steps of melting the first region, removing the first powder from the second region, and laying the second powder. Similarly, in the k-th layer, there is no sequential order between melting the first region or the second region; both can achieve the technical effect of this invention and fall within the protection scope of this invention.

[0014] In some embodiments, preferably, the powder is selected such that D150-D250≥10 μm, and the laser beam is selected such that B1=m1×D150, 2≤m1≤10; B2=m2×D250, 1≤m2≤3; and B1-B2≥25 μm. Existing technologies typically do not address the issue of selecting the laser beam diameter for the zonal melting of coarse and fine powders, which requires consideration of forming accuracy, forming quality, and efficiency. Compared to the aforementioned basic technical solutions, this preferred technical solution comprehensively limits the differences in particle size between coarse and fine powders, the matching relationship between the laser beam size and the powder particle size, and the difference in beam size. This enables a graded and adaptive, zoned and coordinated process mechanism between the coarse and fine powder regions in terms of laser input, molten pool forming scale, and powder melting stability. By controlling the difference in average powder particle size and beam diameter, a stable and clear zoning can be achieved, which is beneficial for shape and property control. Establishing a matching relationship between the beam diameter and the corresponding average powder particle size allows the laser input to be adapted to the powder particle size and powder melting characteristics. This avoids problems such as insufficient fusion, low density, and low forming efficiency in coarse powder due to an excessively small beam, while also preventing a decrease in dimensional accuracy and quality in fine powder due to an excessively large beam.

[0015] In some embodiments, more preferably, the powder and laser beam are selected such that 2×(D150-D250)≤(B1-B2). By further optimizing and limiting the matching relationship between the powder particle size difference and the laser beam diameter difference, problems such as limited melting efficiency of coarse powder and limited improvement of melting precision of fine powder caused by insufficient beam difference due to large particle size differences can be further avoided. This is conducive to increasing the melting process window of the coarse powder area and is more conducive to the simultaneous improvement of precision and quality of fine area, forming stability and density of coarse powder area, and forming efficiency of overall component. Through the mutual constraint and matching of multiple parameters, the comprehensive technical effect of high-precision forming of fine area and efficient and stable forming of coarse powder area in the coarse and fine powder partitioning process is better realized. The above-mentioned correlation limitation is not a simple combination of conventional process parameters, but a targeted control method based on the coupling law of powder particle size-beam diameter-molten pool in powder bed melting forming. It effectively solves the technical problem of the incoordination between beam size difference and powder particle size and the difficulty in balancing precision and stability when forming coarse and fine powder partitions.

[0016] In some embodiments, preferably, the thickness of the forming layer in the first region is T1 = n1 × (ρ1 / ρ 10)×D190, the thickness of the forming layer in the second region is T2= n2×(ρ2 / ρ 20 ) × D290, 1.5≤n1≤2.5, 1.0≤n2≤1.5, D190 and D290 are the particle sizes corresponding to the cumulative distribution ratio of the volume fraction of the first powder and the second powder reaching 90%, respectively, ρ1 and ρ2 are the loose pack densities of the first powder and the second powder, respectively, ρ 10 ρ 20 These are the densities of the first powder and the second powder, respectively. The first powder and the second powder can be the same or different. When the first powder and the second powder are the same, ρ... 10 =ρ 20 .

[0017] Existing technologies typically select layer thickness based on experience. In the optimized technical solution, a differentiated layer thickness quantitative calculation formula is specifically established that is strongly correlated with the D90 particle size, loose packing density, and material density of the powder in the first and second regions. This establishes a method for layer thickness selection, avoids the uncertainty of layer thickness selection, and better achieves a deep fit between layer thickness design and the melting characteristics of coarse and fine powders, the precision requirements of the forming area, and the forming efficiency. At the same time, it ensures the powder spreading quality and melting quality of the two regions, avoiding problems such as poor powder spreading quality, melt porosity, insufficient density, and surface roughness. This ensures the overall density and mechanical properties of the part, and further achieves the matching of part zoning precision, the improvement of overall density and mechanical properties, and the synergistic optimization of forming efficiency, so that the process advantages of coarse and fine powder zoning melting can be fully utilized.

[0018] In some embodiments, the second region may optionally include the outer surface contour, inner flow channel, and cell structure portion of the part to be formed; the first region is the remaining forming region on the slice layer excluding the second region.

[0019] In existing technologies, when using laser powder bed fusion molding to achieve high-precision internal channels, cellular structures, microporous structures, or high surface quality parts, forming efficiency is often sacrificed. This problem is particularly pronounced when preparing large-sized parts (at least one direction with a length ≥200 mm), significantly extending forming time and increasing forming costs, thus greatly limiting the widespread application of these fine structures in various fields. This invention enables the simultaneous forming of fine and non-precision structures. Specifically, for fine structures requiring high forming accuracy and surface quality, such as internal channels, cellular structures, and microporous structures, fine powder and a small-sized laser beam are used for layer-by-layer melting. For other structures, such as the interior of the part, which do not require high precision, coarse powder and a large-sized laser beam are used for concentrated melting, significantly improving forming efficiency. It should be noted that the application scenarios of the present invention are not limited to the internal flow channels, cell structure parts, and microporous structures listed above. The technical solution of the present invention can be adopted in any laser powder bed melting forming scenario where the surface quality or fine structure of the part to be formed is required, and the forming efficiency needs to be taken into account.

[0020] In some embodiments, for example, the first powder comprises a continuously graded powder with a particle size range of 15–53 μm or 53–150 μm, and the second powder comprises a continuously graded powder with a particle size range of 10–25 μm or 15–53 μm; and it is ensured that the average particle size D150 of the first powder is greater than the average particle size D250 of the second powder. When the second powder has a particle size of 10–25 μm, the first powder is a continuously graded powder with a particle size range of 15–53 μm or 53–150 μm; when the second powder has a particle size of 15–53 μm, the first powder is a continuously graded powder with a particle size range of 53–150 μm. Optionally, the diameter B1 of the first laser beam is 100~300 μm, and the diameter B2 of the second laser beam is 20~80 μm. In addition to a laser beam diameter of 60~80 μm, the second laser beam can also use a laser beam diameter of 20~60 μm, or further, for example, laser beam diameters of 20~50 μm, 20~40 μm, 20~30 μm, 30~40 μm, 40~50 μm, 50~60 μm, etc. Specifically, the laser beam diameter can be 20 μm, 30 μm, 40 μm, 50 μm, or any point value within the above range.

[0021] Existing laser powder bed melting processes typically use beam diameters of 60-80 μm. This invention focuses on the synergistic relationship between laser beam diameter and coarse and fine powders. By matching laser beams of different sizes to the differences in particle size characteristics, packing properties, and melting behavior of coarse and fine powders, it achieves adaptation between the heat source scale and powder characteristics. Specifically, for the aforementioned coarse powder particle size, the beam diameter in the coarse powder region is preferably set to 100-300 μm. By increasing the beam diameter, the continuity of the molten pool, the sufficiency of melting, and efficiency are ensured, avoiding defects such as porosity, incomplete fusion, and low density caused by the mismatch between the beam and powder particle size. The beam diameter in the fine powder region is set to 20-80 μm. In addition to using a 60-80 μm laser beam diameter, it proposes using smaller beam sizes, including 20-60 μm, to further improve forming accuracy and surface quality. The aforementioned graded and coordinated design of beam diameter and powder particle size breaks through the technical limitations of traditional laser powder bed melting processes, where a single beam cannot simultaneously ensure the forming quality of coarse powder and the structural precision of fine powder. It optimizes the forming stability of the molten pool from the essential level of heat source-powder matching, and achieves simultaneous assurance of efficient and reliable forming in the coarse powder region and high-precision forming in the fine powder region.

[0022] In some embodiments, more preferably, the second powder is a 10-25 μm continuously graded powder, and the diameter B2 of the second laser beam is 20-30 μm. In an even more preferred embodiment, a 10-25 μm continuously graded powder is used in the second region to match a fine spot size of 20-30 μm. Compared with existing technologies, this allows for more precise control of the size and morphology of the molten pool, enabling high-precision forming of fine structures such as internal channels and cell structures, thus overcoming the precision bottleneck of conventional laser beams in fine structure forming.

[0023] To achieve the above-mentioned technical effects, the present invention also provides an additively manufactured part, which is prepared by the additive manufacturing method described above.

[0024] In some embodiments, the minimum flow channel diameter of the inner flow channel of the part is ≤1 mm, and the minimum structural diameter or width of the cell structure of the part is ≤0.15 mm. When forming the above-mentioned fine structure, the present invention employs a small-sized laser beam, especially a fine spot, and through the synergistic effect of the fine spot and finer powder, it can accurately achieve the melting and forming of the above-mentioned fine structure, producing a fine structure with high dimensional accuracy and excellent surface quality, further highlighting the technical advantages of the present invention in the field of fine structure forming.

[0025] To achieve the above-mentioned technical effects, the present invention also provides an additive manufacturing system for partitioned melting of coarse and fine powders, used to implement the additive manufacturing method, comprising: The forming chamber is used for laser powder bed melting forming of the part to be formed; The powder silo includes a coarse powder silo and a fine powder silo, wherein the coarse powder silo is used to store a first powder and the fine powder silo is used to store a second powder; A powder spreading system is used to spread the first powder in the coarse powder bin to the entire powder bed, and to transport the second powder in the fine powder bin to the second area of ​​the corresponding layer; A powder removal device for removing the first powder spread to the second region; An optical system is used to output at least two laser beams with different diameters to perform partitioned melting of a first powder in a first region and a second powder in a second region, respectively. The control system is connected to the forming chamber, powder chamber, powder laying system, powder removal device, and optical system. Based on the slicing path of the workpiece to be formed and the division of the first and second regions, the control system automatically controls the coordinated operation of each component, so that the second region completes the laser melting forming of each layup layer by layer. After the melting of k layups in the second region is completed, the first region corresponding to the k layup thicknesses is subjected to a concentrated laser melting forming.

[0026] In some embodiments, preferably, a powder recovery system is also included. This powder recovery system is connected to the control system and is used to classify and recover powder to corresponding coarse or fine powder silos. The recovered powder originates from two sources: powder collected in the powder overflow silo during the laser powder bed melting process and powder from the formed powder bed. After forming, the powder from the formed powder bed can be further cleaned into the powder overflow silo for processing by the powder recovery system. This powder recovery system effectively reduces powder waste, improves powder utilization, and further reduces the forming cost of the parts, thus enhancing the economy and practicality of the present invention.

[0027] To achieve the above-mentioned technical effects, the present invention also provides an application of additive manufacturing parts made by partitioning and melting coarse and fine powders in the fields of aerospace, automotive, consumer electronics, marine, medical, and mold making. The additive manufacturing parts are made by the additive manufacturing method described in the present invention. The present invention can accurately match the performance requirements of various fields, while giving full play to the core technical effects of "ensuring accuracy, improving efficiency, and reducing costs". In the aerospace field, there are high requirements for lightweight and precision components. For components such as aero-engine nozzles, aero-engine booms, aero-engine casings, aero-engine bladed disks, aero-engine blades, aero-engine tailpipes, and aero-engine radiators, the fine internal flow channels, cellular structures, and fine micropores can be divided into a second region, where fine powder and small-size lasers ensure precision. The remaining structures are divided into a first region, where coarse powder and large-size laser melting improve efficiency and reduce costs. In the automotive field, lightweighting and energy efficiency are pursued. For components such as cylinder blocks, the internal flow channel area can be divided into a second region, while the remaining parts are divided into a first region, balancing structural strength and forming efficiency, reducing weight and lowering powder costs. In the consumer electronics field, exquisite appearance and complex structures are required. The casings and brackets of electronic devices can be finely formed with fine powder to ensure texture, while coarse powder can be used to form the internal structure to improve efficiency. In the marine field, components need corrosion resistance and high strength. In the medical field, personalized and precise devices are required. In the mold field, high-precision internal flow channels and short development cycles are required. This invention can adapt coarse and fine powders by partitioning them, meeting the stringent performance requirements of various fields while significantly improving forming efficiency and reducing manufacturing costs. It should be understood that the above examples are merely illustrative and, based on the technical concept of this invention, are also applicable to other high-end component manufacturing fields that require both precision in fine structures and overall manufacturing efficiency.

[0028] Compared with the prior art, one or more technical solutions of the present invention have at least one of the following beneficial effects: 1. In the basic technical solution of this invention, by dividing the forming area and adopting a process of separate powder spreading for coarse and fine powders and laser zone melting, the core problem of traditional laser powder bed melting technology—that it is impossible to balance accuracy and overall forming efficiency, as well as the full utilization of coarse powder when using a single powder, a single laser, or a single powder with dual lasers—is solved. Targeting the characteristics of coarse and fine powders, the second area uses fine powder and a small-sized laser beam for layer-by-layer melting, while the first area uses coarse powder and a large-sized laser beam for concentrated melting. Combined with the linkage control of layer thickness multiple and forming sequence, the matching of powder and beam ensures melting quality and efficiency, and the differentiated layer thickness setting further reduces forming time. This invention breaks through the traditional laser powder bed melting process's single powder, single laser, and equal-thickness layer-by-layer melting mode, achieving efficient forming and utilization of coarse powder, solving the problems of coarse powder waste and high cost of customized powder in traditional processes, and simultaneously achieving a comprehensive effect that balances coarse powder utilization, forming accuracy, forming quality, and efficiency.

[0029] 2. Several preferred technical solutions construct a multi-dimensional control system encompassing powder particle size, laser beam diameter, forming area, layer thickness, and forming timing. By quantitatively defining the compatibility between powder particle size and laser beam diameter, and further establishing differentiated layer thickness calculation relationships related to powder characteristics, effective control of the molten pool morphology and temperature gradient is achieved. This effectively resolves the contradiction in the compatibility of coarse and fine powder melting, ensuring powder spreading quality and melt quality. This results in improved part zoning accuracy, overall density, mechanical properties, and synergistic optimization of forming efficiency. In some preferred solutions, stable and efficient forming of fine structures with a minimum internal flow channel diameter ≤1 mm and a minimum cell structure size ≤0.15 mm is achieved, providing strong support for the widespread application of laser powder bed melting technology in the field of efficient fine structure forming.

[0030] 3. This invention provides an integrated design for an additive manufacturing system. Addressing the concept of separating coarse and fine powders, it facilitates the separate laying of coarse and fine powders within the same powder bed through a powder laying system and a powder removal device. In a preferred embodiment, a powder grading and recycling system is also included to achieve powder grading, sieving, directional recycling, and reuse. This solves the problem of indiscriminate powder recycling in traditional processes, which cannot be adapted to zonal forming, further improving the overall powder utilization rate, forming full-process powder cost control, and reducing the overall production cost of manufactured parts.

[0031] 4. This invention enables the simultaneous and efficient forming of fine structures and large-size, meter-level components, overcoming the application limitations of conventional equipment in terms of insufficient precision and efficiency. It has strong process adaptability and a high degree of automation, and can be widely used in aerospace, automotive, consumer electronics, marine, medical, mold and other fields. It further meets the forming requirements of fine structures such as fine internal flow channels, fine lightweight cell structures, and fine microporous structures. It is especially suitable for the stringent requirements of high-end key components such as aero-engine casings, nozzles, and bladed disks, and has significant technical value and promising industrial application prospects. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the additive manufacturing system for partitioned melting of coarse and fine powders in the embodiment; Figure 2 This is a schematic diagram of the first internal region and the second edge region of the part in the embodiment; Figure 3 This is a schematic diagram of the first region of the component entity and the second region of the sperm cell in the embodiment; Among them, 1. First area; 2. Second area; 3. First laser beam; 4. Second laser beam; 5. Forming chamber; 6. Coarse powder silo; 7. Fine powder silo; 8. Powder removal device; 9. Powder overflow silo; 10. Control system. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments. All technologies implemented based on the content of the present invention fall within the scope of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance.

[0034] See Figures 1 to 3 An additive manufacturing method for partitioned melting of coarse and fine powders, comprising: The 3D model of the part to be formed is sliced ​​into layers to obtain the slicing path of each layer; Based on the forming accuracy requirements of the part to be formed, the forming area in each slice is divided into the first region 1 and the second region 2. In the process of melting and forming the part to be formed using laser powder bed melting technology, the powder formed in the first region 1 is the first powder, and the powder formed in the second region 2 is the second powder. The average particle size D150 of the first powder is greater than the average particle size D250 of the second powder. D150 and D250 are the particle sizes corresponding to the cumulative distribution ratio of the volume fraction of the first powder and the second powder, respectively, reaching 50%. The diameter B1 of the first laser beam is greater than the diameter B2 of the second laser beam. Specifically, D150-D250≥10 μm, B1=m1×D150, 2≤m1≤10; B2=m2×D250, 1≤m2≤3; B1-B2≥25 μm; 2×(D150-D250)≤(B1-B2).

[0035] The layer thickness of the first region is T1, and the layer thickness of the second region is T2, where T1 = n1 × (ρ1 / ρ 10 )×D190,T2= n2×(ρ2 / ρ 20 ) × D290, 1.5≤n1≤2.5, 1.0≤n2≤1.5, D190 and D290 are the particle sizes corresponding to the cumulative distribution ratio of the volume fraction of the first powder and the second powder reaching 90%, respectively, ρ1 and ρ2 are the loose pack densities of the first powder and the second powder, respectively, ρ 10 ρ 20Let T1 and T2 be the densities of the first powder and the second powder, respectively. T1 and T2 are preferably integers. The first powder and the second powder can be the same or different. When the first powder and the second powder are the same, ρ... 10 =ρ 20 .

[0036] In this embodiment, by dividing the slice of the part to be formed into forming areas, metal powders of different particle sizes are selected in different areas of the part to be formed, and lasers of different beam diameters are matched to achieve graded and regional independent control of powder and laser, thereby improving manufacturing efficiency and reducing production costs while ensuring forming accuracy, and achieving efficient utilization of coarse powder.

[0037] In this embodiment, the second region 2 is a region with high forming accuracy requirements, including the outer surface contour, inner flow channel, cell structure, microporous structure, etc. of the part to be formed, and the first region 1 is the other regions on the slice layer except for the second region 2.

[0038] The thickness of the first region 1 layer is k times the thickness of the second region 2 layer (k is a positive integer, k≥2); during forming, the first powder is simultaneously laid on the first region 1 and the second region 2 in the first layer of the powder bed; the first powder in the second region 2 in the current layer is removed, the second powder is laid on the second region 2 and leveled, and the second laser beam is used to perform laser melting forming on the second region, while the first region is not laser melting forming for the time being. When k=2, the first powder is simultaneously laid in the first region 1 and the second region 2 of the second layer of the powder bed, the first powder in the second region 2 is removed, the second powder is laid in the second region 2 and leveled, the second laser beam is used to perform laser melting and forming on the second region 2, and the first laser beam is used to perform single concentrated laser melting and forming on the first region 1. Alternatively, the first powder is simultaneously laid in the first region 1 and the second region 2 of the second layer of the powder bed, and the first laser beam is used to perform a single concentrated laser melting and forming on the first region 1. The first powder in the second region 2 is removed, the second powder is laid in the second region 2 and leveled, and the second laser beam is used to perform laser melting and forming on the second region. This process is repeated until the entire part to be formed is finally completed; When k>2, the first powder is continuously laid simultaneously in the first region 1 and the second region 2 of the second layer of the powder bed. The first powder in the second region 2 is removed, and the second powder is laid and leveled in the second region 2. The second laser beam is used to perform laser melting and forming on the second region 2. The first region 1 is not laser-melted and formed temporarily. Until the kth layer, after the first powder is laid simultaneously in the first region 1 and the second region 2, the first powder in the second region 2 is removed, and the second powder is laid and leveled. The first laser beam is used to perform single-stage concentrated laser melting and forming on the first region 1, and the second laser beam is used to perform laser melting and forming on the second region 2 of the kth layer. Or until the first powder is laid on the first region 1 and the second region 2 in the kth layer, the first laser beam is used to perform a single concentrated laser melting and forming on the first region 1, the first powder in the second region 2 is removed, and then the second powder is laid and leveled, and the second laser beam is used to perform laser melting and forming on the second region of the kth layer. This process is repeated until the entire part to be formed is finally completed.

[0039] For example, when k=3, the first powder is simultaneously laid on the first region 1 and the second region 2 on the powder bed; the first powder in the second region 2 of the current layup is removed, the second powder is laid on the second region 2 and leveled, and the second laser beam is used to perform laser melting and forming on the second region 2, while the first region 1 is not laser-melted and formed temporarily; the first powder is then laid on both the first region 1 and the second region 2 of the second layer powder bed, the first powder in the second region 2 is removed, the second powder is laid on the second region 2 and leveled, and the second laser beam is used to perform laser melting and forming on the second region 2, while the first region 1 is not laser-melted and formed temporarily; until in the third layup, the first powder is simultaneously laid on the first region 1 and the second region 2, the first powder in the second region 2 is removed, the second powder is laid on and leveled, the first laser beam is used to perform single-stage concentrated laser melting and forming on the first region 1, and the second laser beam is used to perform laser melting and forming on the second region 2 of the third layer, and so on, until the forming of the entire part to be formed is finally completed.

[0040] Based on the same inventive concept, such as Figure 1 As shown, this embodiment also provides an additive manufacturing system for partitioned melting of coarse and fine powders, used to implement the additive manufacturing method described above, including: Forming chamber 5 is used for laser powder bed melting forming of the part to be formed; The powder silo includes a coarse powder silo 6 and a fine powder silo 7. The coarse powder silo 6 is used to store a first powder, and the fine powder silo 7 is used to store a second powder. A powder spreading system is used to spread the first powder in the coarse powder bin 6 to the entire powder bed, or to transport the second powder in the fine powder bin 7 to the second region 2 of the corresponding layer; Powder removal device 8 is used to remove the first powder spread to the second region 2; An optical system is used to output at least two laser beams with different diameters to perform partitioned melting of the first powder in the first region 1 and the second powder in the second region 2, respectively.

[0041] The control system 10 is connected to the forming chamber 5, powder chamber, powder laying system, powder removal device 8, and optical system, respectively. The control system has the function of controlling the execution of the method described in this invention. Based on the slicing path of the workpiece to be formed and the division of the first region and the second region, the control system automatically controls the coordinated operation of each component, so that the second region completes the laser melting forming of each layup layer by layer. After the melting of k layup layers in the second region is completed, the first region corresponding to the k layup thicknesses is subjected to a concentrated laser melting forming.

[0042] The additive manufacturing system in this embodiment also includes a powder recovery system. The control system is connected to the powder recovery system. The recovered powder comes from two sources: one is the powder collected in the powder overflow chamber 9 during the laser powder bed melting process, and the other is the powder from the formed powder bed. After forming, the powder from the formed powder bed can be further cleaned into the powder overflow chamber 9. The powder recovery system classifies and recovers the powder in the powder overflow chamber 9 to the corresponding coarse powder chamber 6 or fine powder chamber 7. For example, ultrasonic sieving can be performed using screens with different mesh sizes. The sieved powders of different particle sizes are automatically transported to the corresponding powder chambers for subsequent forming, realizing the automatic recovery and utilization of powders of different particle sizes. This recovery method is particularly suitable for situations where coarse and fine powders are the same material, and it also has good applicability in scenarios where coarse and fine powders are different materials with significant differences in particle size.

[0043] Example 1 This embodiment uses two GH4169 high-temperature alloys with different particle size ranges as examples to illustrate the additive manufacturing method of partitioned melting of coarse and fine powders of the present invention in detail, as follows: The coarse powder (first powder, 53~150 μm, non-spherical powder) is prepared by mechanical crushing or water atomization, with an average particle size D150 of 96 μm, and is placed in the coarse powder hopper 6. The fine powder (second powder, 15~53 μm, spherical powder) is prepared by air atomization, with an average particle size D250 of 30 μm, and is placed in another fine powder hopper 7.

[0044] The preparation process is as follows: The data model of the part is sliced. According to the requirements of the part, the solid part inside each slice is divided into the first region 1, and the edge contour part (2 mm away from the outer contour surface) is divided into the second region 2. The laser melting path planning of each slice is processed, and the processed data is imported into the laser powder bed melting equipment.

[0045] The layer thickness of the first region is set to T1, and the layer thickness of the second region is set to T2. Where T1 = n1 × (ρ1 / ρ 10 ) × D190 (1.5≤n1≤2.5), ρ1 is the first loose powder density, ρ 10 The density of the first powder material (GH4169 is taken as 8.24 g / cm³) is given. 3 The calculated T1 is rounded to the nearest integer, and T2 = n2 × (ρ2 / ρ) 20 )×D290 (1.0≤n2≤1.5), ρ2 is the second powder loose density, ρ 20 The density of the second powder material (ρ) 20 =ρ 10 GH4169 was taken as 8.24 g / cm³. 3 The calculated T2 is rounded to the nearest integer. The particle sizes D10, D50, and D90 of the powder were obtained using a laser particle size analyzer, and the loose packing density of the powder was obtained using a Hall effect flow meter. The first powder had a D190 of 135 μm and a loose packing density ρ1 of 3.54 g / cm³. 3 1.5≤n1≤2.5, the thickness of layer T1 ranges from 87 to 145 μm, the second powder D290 is 52 μm, and the loose packing density ρ2 of the second powder is 4.53 g / cm³. 3 1.0≤n2≤1.5, the layer thickness T2 ranges from 29 to 43 μm. Taking T1 as 90 μm and T2 as 30 μm, the layer thickness of the first region is three times that of the second region.

[0046] The specific steps are as follows: Figure 2In the first layer, 53-150 μm non-spherical coarse powder is spread in both the first region 1 and the second region 2. Then, the coarse powder is removed from the second region 2, and 15-53 μm spherical fine powder is spread on top. The powder is then leveled with a scraper, and a small-sized laser beam (second laser beam 4) is used to melt the powder in the second region 2, without forming the first region 1 yet. The second layer repeats the powder spreading and forming process similar to the first layer, without forming the first region 1 yet. In the third layer, coarse powder is spread in both the first region 1 and the second region 2. The solid portion of the first region 1 is then melted with a large-sized laser beam (first laser beam 3) to form the first region 1. After forming the first region 1, the coarse powder corresponding to the edge contour of the second region 2 is removed using a powder removal device 8. Then, fine powder is conveyed to the designated second region 2 by airflow powder feeding, and the fine powder in the second region 2 is leveled with a scraper and melted with a small-sized laser beam (second laser beam 4). The large-sized laser beam (first laser beam 3) has a diameter of 200 μm, and the small-sized laser beam (second laser beam 4) has a diameter of 65 μm. Then, the fourth layer repeats the powder laying and shaping process similar to the first layer, the fifth layer repeats the powder laying and shaping process similar to the second layer, and the sixth layer repeats the powder laying and shaping process similar to the third layer. This process is repeated until the GH4169 part is finally formed.

[0047] Example 2 This embodiment uses two TC4 titanium alloys with different particle size ranges as examples to describe in detail the additive manufacturing method of partitioned melting of coarse and fine powders of the present invention, as follows: Spherical coarse powder (53~150 μm) is prepared by gas atomization and has an average particle size D150 of 103 μm. It is placed in coarse powder hopper 6. Fine powder (15~53 μm, spherical powder) is prepared by gas atomization and has an average particle size D250 of 32 μm. It is placed in another fine powder hopper 7.

[0048] like Figure 2 According to the requirements of the part, the solid part inside each layer of the part slice is divided into the first region 1, and the edge contour part (2 mm away from the outer contour surface) is divided into the second region 2.

[0049] The data model of the part is sliced ​​and path planning is performed, and the processed data is imported into the laser powder bed melting equipment.

[0050] The layer thickness of the first region is T1, and the layer thickness of the second region is T2, where T1 = n1 × (ρ1 / ρ 10 ) × D190 (1.5≤n1≤2.5), ρ1 is the first loose powder density, ρ 10 The density of the first powder material (TC4 is 4.42 g / cm³) 3The calculated T1 is rounded to the nearest integer, and T2 = n2 × (ρ2 / ρ) 20 )×D290 (1.0≤n2≤1.5), ρ2 is the second powder loose density, ρ 20 The density of the second powder material (ρ) 20 =ρ 10 TC4 was 4.42 g / cm³. 3 The calculated T2 is rounded to the nearest integer. The particle sizes D10, D50, and D90 of the powder were obtained using a laser particle size analyzer, and the loose packing density of the powder was obtained using a Hall effect flow meter. The first powder had a D190 of 141 μm and a loose packing density ρ1 of 2.08 g / cm³. 3 1.5≤n1≤2.5, layer thickness T1 ranges from 100 to 166 μm, second powder D290 is 56 μm, and the loose packing density ρ2 of the second powder is 2.48 g / cm³. 3 1.0≤n2≤1.5, the layer thickness T2 ranges from 31 to 47 μm, the layer thickness T1 is taken as 120 μm, the layer thickness T2 is taken as 40 μm, and the layer thickness of the first region is three times that of the second region.

[0051] The specific procedure is as follows: In the first layer, 53-150 μm spherical coarse powder is spread in both the first region 1 and the second region 2. The coarse powder is removed from the second region 2, and 15-53 μm spherical fine powder is spread and leveled. Then, a small-sized laser beam is used to melt the powder in the second region 2, without forming the first region 1. The second layer repeats the powder spreading and forming process similar to the first layer, without forming the first region 1. In the third layer powder bed, coarse powder is spread in both the first region 1 and the second region 2. Then, the solid portion of the first region 1 is melted using a large-sized laser beam to form the first region 1. After forming the first region 1, the coarse powder corresponding to the edge contour of the second region 2 is removed using a powder removal device 8. Then, fine powder is transported to the designated second region 2 and leveled using an airflow powder conveying method, and melted using a small-sized laser beam (second laser beam 4). The large-sized laser beam (first laser beam 3) has a diameter of 286 μm, and the small-sized laser beam (second laser beam 4) has a diameter of 72 μm. Then, the fourth layer repeats the powder laying and shaping process similar to the first layer, the fifth layer repeats the powder laying and shaping process similar to the second layer, and the sixth layer repeats the powder laying and shaping process similar to the third layer. This process is repeated until the TC4 part is finally formed.

[0052] In addition, after the forming process is completed, the powder from the formed powder bed is further cleaned into the powder overflow chamber 9. The powder recovery system classifies and recovers the powder in the powder overflow chamber 9 to the corresponding coarse powder chamber 6 or fine powder chamber 7, thereby improving the powder utilization rate.

[0053] Example 3 This embodiment uses two TA15 titanium alloys with different particle size ranges as examples to describe in detail the additive manufacturing method of partitioned melting of coarse and fine powders of the present invention, as follows: Coarse powder (15~53 μm, spherical powder, prepared by gas atomization) is placed in coarse powder hopper 6, with an average particle size D150 of 32 μm. Fine powder (10~25 μm, spherical powder, prepared by gas atomization) is placed in another fine powder hopper 7, with an average particle size D250 of 16 μm.

[0054] According to the requirements of the part, the solid portion of each layer of the part slice is divided into the first region 1, and the fine lightweight cellular structure is divided into the second region 2, such as... Figure 3 As shown.

[0055] The data model of the part is sliced ​​and path planning is performed, and the processed data is imported into the laser powder bed melting equipment.

[0056] The layer thickness of the first region is T1, and the layer thickness of the second region is T2. Where T1 = n1 × (ρ1 / ρ 10 ) × D190 (1.5≤n1≤2.5), ρ1 is the first loose powder density, ρ 10 The density of the first powder material (TA15 is taken as 4.45 g / cm³) 3 The calculated T1 is rounded to the nearest integer, and T2 = n2 × (ρ2 / ρ) 20 )×D290 (1.0≤n2≤1.5), ρ2 is the second powder loose density, ρ 20 The density of the second powder material (ρ) 20 =ρ 10 TA15 was 4.45 g / cm³. 3 The calculated T2 is rounded to the nearest integer. The particle sizes D10, D50, and D90 of the powder were obtained using a laser particle size analyzer, and the loose packing density of the powder was obtained using a Hall effect flow meter. The first powder had a D190 of 47 μm and a loose packing density ρ1 of 2.49 g / cm³. 3 1.5≤n1≤2.5, T1 layer thickness ranges from 40 to 66 μm, the second powder D290 is 26 μm, and the loose packing density ρ2 of the second powder is 2.46 g / cm³. 3 1.0≤n2≤1.5, the thickness of layer T2 ranges from 14 to 22 μm, the thickness of layer T1 is 40 μm, the thickness of layer T2 is 20 μm, and the thickness of layer T1 is twice that of layer T2.

[0057] The specific procedure is as follows: In the first layer, 15-53 μm spherical coarse powder is spread in both the first region 1 and the second region 2. Then, the coarse powder is removed from the second region 2, and 10-25 μm spherical fine powder is spread and leveled. A small-sized laser beam is then used to melt the powder in the second region 2, without forming the first region 1. In the second layer, coarse powder is spread in both the first and second regions of the powder bed. Then, a large-sized laser beam is used to melt the powder in the first region 1, forming the first region 1. After forming the first region 1, the coarse powder corresponding to the fine lightweight cell units in the second region 2 is removed using a powder removal device 8. Then, the fine powder is transported to the designated second region 2 and leveled using an airflow powder conveying method. The second region is then melted using a small-sized laser beam. The large-sized laser beam (first laser beam 3) has a diameter of 70 μm, and the small-sized laser beam (second laser beam 4) has a diameter of 30 μm. The third layer repeats the powder spreading and forming process similar to the first layer, and the fourth layer repeats the same process. This cycle is repeated until the TA15 part is finally formed, with the diameter of the rods in the fine lattice ≤0.10 mm.

[0058] In addition, after the forming process is completed, the powder from the formed powder bed is further cleaned into the powder overflow chamber 9. The powder recovery system classifies and recovers the powder in the powder overflow chamber 9 to the corresponding coarse powder chamber 6 or fine powder chamber 7, thereby improving the powder utilization rate.

[0059] In summary, Examples 1 to 3 respectively used powders of three different materials: GH4169 high-temperature alloy, TC4 titanium alloy, and TA15 titanium alloy as research objects. These examples divided the forming area of ​​the part into a first region and a second region. Coarse powder was used in conjunction with a large-size laser beam for concentrated melting and forming in the first region, while fine powder was used in conjunction with a small-size laser beam for layer-by-layer melting and forming in the second region. Preferably, by establishing a quantitative adaptation relationship between the average particle size of the powder and the size of the laser beam, and by establishing differentiated layer thicknesses directly related to the loose packing density and D90 particle size of the first and second regions, the powder spreading quality and melting quality of the two regions were ensured. This fully realized the precise matching of part partitioning accuracy, the improvement of overall density and mechanical properties, and the synergistic optimization of forming efficiency, thus giving full play to the technological advantages of partitioned melting of coarse and fine powders. Through implementation verification with different materials and different fine structure types, it was demonstrated that the technical solution of this invention can be widely adapted to various laser powder bed melting forming scenarios that require both forming efficiency and fine structure quality and accuracy. It can provide reliable practical support for the promotion and application of laser powder bed melting technology in the field of fine structure forming.

[0060] Furthermore, the technical solution of this invention can effectively utilize coarse powder, achieving cost reduction and efficiency improvement while stably and efficiently forming parts with high dimensional accuracy and excellent surface quality. In particular, as shown in Example 3, by preferably using finer powder in the fine powder region to match a fine laser spot, it is possible to successfully prepare fine lattice cells with a rod diameter ≤0.10 mm. Through the precise matching of powder and light, the accuracy bottleneck of conventional laser beams in fine structure forming can be overcome, realizing the preparation of ultra-fine structures. This invention can solve the technical problems in the existing technology of balancing efficiency, quality, and accuracy in fine structure preparation, and the difficulty in fully utilizing coarse powder, greatly improving production efficiency and reducing production costs. It provides a new approach for the low-cost, high-efficiency, and high-quality forming of fine structures such as fine internal channels, fine lightweight cell structures, and fine microporous structures using LPBF technology.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An additive manufacturing method for partitioned melting of coarse and fine powders, characterized in that, include: The 3D model of the part to be formed is sliced ​​into layers to obtain the slicing path of each layer. The forming area in each slice is divided into the first region and the second region. In the process of melting and forming the part to be formed using laser powder bed melting technology, the forming powder in the first region is the first powder, and the forming powder in the second region is the second powder. The first powder includes continuously graded powder with a particle size range of 15~53 μm or 53~150 μm, and the second powder is continuously graded powder with a particle size range of 10~25 μm. D150 and D250 are the particle sizes corresponding to the cumulative distribution ratio of volume fraction in the first powder and the second powder, respectively, reaching 50%. A first laser beam is used to laser scan and shape a first region, and a second laser beam is used to laser scan and shape a second region. The diameter B1 of the first laser beam is larger than the diameter B2 of the second laser beam. The powder is selected such that D150 - D250 ≥ 10 μm, and the laser beam is selected such that B1 = m1 × D150, 2 ≤ m1 ≤ 10; B2 = m2 × D250, 1 ≤ m2 ≤ 3; and B1 - B2 ≥ 25 μm. The powder and laser beam are selected such that 2 × (D150 - D250) ≤ (B1 - B2). The layer thickness T1 of the first region is k times the layer thickness T2 of the second region, where k is a positive integer, k ≥ 2, and the layer thickness T1 of the first region is n1 × (ρ1 / ρ2). 10 )×D190, the thickness of the forming layer in the second region is T2= n2×(ρ2 / ρ 20 ) × D290, 1.5≤n1≤2.5, 1.0≤n2≤1.5, D190 and D290 are the particle sizes corresponding to the cumulative distribution ratio of the volume fraction of the first powder and the second powder reaching 90%, respectively, ρ1 and ρ2 are the loose pack densities of the first powder and the second powder, respectively, ρ 10 ρ 20 The densities of the first powder and the second powder are respectively; The first powder is simultaneously laid in the first and second regions of the powder bed in the first layer. The first powder in the second region of the current layup is removed. The second powder is then laid in the second region and leveled. The simultaneous laying of the first powder in the first and second regions is achieved by using a powder laying system to spread the first powder in the coarse powder hopper to the entire powder bed. The laying and leveling of the second powder in the second region is achieved by conveying the second powder to the designated second region by airflow and leveling it with a scraper. The second region is formed by laser melting of each layup layer by layer. The first region is formed by concentrated laser melting of the corresponding k layup thicknesses. This process is repeated until the final part is formed.

2. The additive manufacturing method according to claim 1, characterized in that, After the forming process is completed, the powder in the formed powder bed is further cleaned into the powder overflow bin. The powder recovery system performs ultrasonic sieving through screens with different mesh sizes, and the powder in the powder overflow bin is graded and recovered to the corresponding coarse powder bin or fine powder bin.

3. The additive manufacturing method according to claim 1, characterized in that, When k=2, the first powder is simultaneously spread in the first and second regions of the second layer of the powder bed, the first powder in the second region is removed, the second powder is transported to the designated second region by airflow and leveled with a scraper, the second laser beam is used to perform laser melting and forming on the second region, and the first laser beam is used to perform single-stage concentrated laser melting and forming on the first region. Alternatively, the first powder is simultaneously laid in the first and second regions of the second layer of the powder bed, and the first laser beam is used to perform a single concentrated laser melting and forming on the first region. The first powder in the second region is removed, and the second powder is transported to the designated second region by airflow powder feeding and leveled with a scraper. The second laser beam is then used to perform laser melting and forming on the second region. This process is repeated until the entire part to be formed is finally completed; When k>2, the first powder is simultaneously laid on the first and second regions of the second layer of the powder bed. The first powder in the second region is removed, and the second powder is conveyed to the designated second region by airflow and leveled with a scraper. The second laser beam is used to perform laser melting and forming on the second region. The first region is not laser-melted and formed temporarily. Until the kth layer, after the first powder is simultaneously laid on the first and second regions, the first powder in the second region is removed, and the second powder is conveyed to the designated second region by airflow and leveled with a scraper. The first laser beam is used to perform single-stage concentrated laser melting and forming on the first region, and the second laser beam is used to perform laser melting and forming on the second region of the kth layer. Or until the first powder is laid on the first region and the second region simultaneously in the k-th layer, the first laser beam is used to perform a single concentrated laser melting and forming on the first region, the first powder in the second region is removed, and then the second powder is transported to the designated second region by airflow powder feeding and leveled with a scraper, and the second laser beam is used to perform laser melting and forming on the second region of the k-th layer. This process is repeated until the entire part to be formed is finally completed.

4. The additive manufacturing method according to any one of claims 1 to 3, characterized in that, The second region includes the outer surface contour, inner flow channel, and cell structure of the part to be formed; the first region is the remaining forming region on the slice layer excluding the second region.

5. The additive manufacturing method according to claim 4, characterized in that, The diameter B1 of the first laser beam is 100~300 μm, and the diameter B2 of the second laser beam is 20~30 μm.

6. An additively manufactured part, characterized in that, It is prepared by the additive manufacturing method according to any one of claims 1 to 4.

7. An additively manufactured part, characterized in that, The part is prepared by the additive manufacturing method according to claim 5, wherein the minimum diameter of the inner flow channel is ≤1 mm, and the minimum structural diameter or width of the cell structure is ≤0.15 mm.

8. An additive manufacturing system for partitioned melting of coarse and fine powders, used to implement the additive manufacturing method according to any one of claims 1 to 5, characterized in that, include: The forming chamber is used for laser powder bed melting forming of the part to be formed; The powder silo includes a coarse powder silo and a fine powder silo, wherein the coarse powder silo is used to store a first powder and the fine powder silo is used to store a second powder; A powder spreading system is used to spread the first powder in the coarse powder bin to the entire powder bed, and to transport the second powder in the fine powder bin to the second area of ​​the corresponding layer; A powder removal device for removing the first powder spread to the second region; An optical system is used to output at least two laser beams with different diameters to perform partitioned melting of a first powder in a first region and a second powder in a second region, respectively. The powder recovery system uses ultrasonic sieving with screens of different mesh sizes to classify and recover the powder in the powder overflow bin to the corresponding coarse powder bin or fine powder bin. The control system is connected to each of the above-mentioned components, including the forming chamber, powder chamber, powder laying system, powder removal device, optical system, and powder recovery system. Based on the slicing path of the workpiece to be formed and the division of the first and second regions, the control system automatically controls the coordinated operation of each component, so that the second region completes the laser melting forming of each layup layer by layer. After the melting of k layups in the second region is completed, the first region corresponding to the k layup thicknesses is subjected to a concentrated laser melting forming.

9. An additive manufacturing process for parts produced by partitioned melting of coarse and fine powders, applicable to aerospace, automotive, consumer electronics, marine, medical, and mold-making fields, characterized in that... The additively manufactured part is obtained by the additive manufacturing method according to any one of claims 1 to 5.

10. An additive manufacturing process using coarse and fine powder partitioning and melting, applied to aero-engine nozzles, aero-engine booms, aero-engine casings, aero-engine bladed disks, aero-engine blades, aero-engine tailpipes, and aero-engine radiators, characterized in that... The additively manufactured part is obtained by the additive manufacturing method according to any one of claims 1 to 5.

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