An absolute heat conduction connection-based lpbf metal additive manufacturing support-free printing method and system

Abstract

The application relates to the technical field of metal additive manufacturing, and discloses an LPBF metal additive manufacturing non-support or extremely weak support printing method and system based on absolute heat conduction connection, which identifies a plurality of heat conduction connection reference areas in the contour range of a slice layer of a 3D model; calculates the minimum Euclidean distances of all to-be-scanned points in the slice layer from all the heat conduction connection reference areas, obtains a plurality of heat conduction distance sets; predefines a heat connection distance threshold value, and screens a plurality of to-be-scanned point sets less than or equal to the heat connection distance threshold value; controls laser to scan the plurality of to-be-scanned point sets according to a preset rule; after the scanning is completed, the to-be-scanned point sets are added to corresponding heat conduction connection reference areas, a plurality of new heat conduction connection reference areas are formed, and re-sorting and scanning are performed until the complete scanning of the whole slice layer. The application realizes controllable weak connection of parts and substrates or internal structures, and improves the reliability and precision of the forming process.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, and in particular to a supportless printing method and system for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection. Background Technology

[0002] In traditional LPBF (Laser Powder Bed Fusion) metal additive manufacturing, ensuring the quality of interlayer and interregional fusion (to avoid incomplete fusion defects) has long relied on empirical scanning strategies and process parameter adjustments, such as island scanning and stripe scanning. While these methods can meet basic forming requirements, they fail to achieve essential and precise control over the physical process of heat conduction, leading to two major technological bottlenecks: First, the residual thermal stress generated by uneven temperature gradients forces the industry to use strong support structures for a long time, which conduct heat through the substrate and bear mechanical loads, becoming a key obstacle to the breakthrough of "supportless printing" technology; second, for special application scenarios such as weakly connected structures and large-size thin-walled parts, existing technologies cannot achieve a precise balance between suppressing thermal deformation (dependence on support structures) and ensuring metallurgical fusion quality, severely restricting the direct manufacturing capability of high-precision, lightweight parts.

[0003] To address these issues, various improvement solutions have been proposed in related fields, but all have significant limitations. For example, the method of fixing multi-layered 3D printed parts to the substrate, using alternating adhesive and printing processes to enhance the substrate connection strength, fails to achieve "extremely weak connections" for the parts to meet the requirement of easy separation later due to reliance on adhesive materials. Furthermore, the adhesive may affect the metallurgical bonding performance of the printed metal, leading to a decrease in the mechanical properties of the parts. Another example is the substrate for embedded LPBF 3D printing. Although the modular design facilitates the replacement of test blocks, it still relies on mechanical fixing methods, making it impossible to achieve a "near-floating" state for the parts. Moreover, the complex substrate structure is not conducive to... For high-precision weak connection requirements; for example, supportless metal 3D printing technology, although it optimizes and reduces support through scanning strategies such as low-angle adaptive partitioning, mainly targets the overhang structure rather than the substrate connection, and does not specifically optimize the substrate connection method. The parts may still be strongly bonded to the substrate due to thermal stress, and traditional vector scanning strategies are difficult to achieve precise weak connection control. The overhang angle and overhang amount of supportless overhang are very limited. There is also LPBF which uses a large overhang feature support structure, and uses toothed contact surfaces and hollow supports to reduce the difficulty of post-processing, but still requires a support structure with strong physical contact, which cannot meet the "near-floating" requirement, and the support removal process may damage the surface of the parts.

[0004] In summary, none of the existing technologies have solved the core contradiction of unsupported printing by addressing the fundamental control of heat conduction, and it is difficult to balance the requirements of fusion quality, thermal deformation suppression, and weak connection / levitation. Summary of the Invention

[0005] This invention provides a supportless printing method and system for LPBF metal additive manufacturing based on absolute thermal conductivity, which is suitable for achieving controllable weak connections between parts and substrates or internal structures, and improving the reliability and accuracy of the molding process.

[0006] This invention provides a supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity, comprising:

[0007] S1. Identify multiple thermal conduction interconnection reference regions within the contour range of the slice layer of the 3D model; wherein, the thermal conduction interconnection reference region is a scanned and completely solidified region immediately adjacent to the lower layer of the slice layer;

[0008] S2. Calculate the minimum Euclidean distance between all points to be scanned in the slice layer and all thermal conduction interconnection reference regions as the thermal conduction distance, and obtain multiple sets of thermal conduction distances based on multiple thermal conduction interconnection reference regions;

[0009] S3. Preset a thermal connection distance threshold, and select a set of points to be scanned that are less than or equal to the thermal connection distance threshold from each set of thermal conduction distances, to obtain multiple sets of points to be scanned;

[0010] S4. Control the laser to scan multiple sets of points to be scanned according to preset rules, and after the scanning is completed, add the sets of points to be scanned to their corresponding heat conduction connection reference regions to form multiple new heat conduction connection reference regions.

[0011] S5. Repeat steps S2 to S4 based on multiple new heat conduction connection reference regions until the entire scan of the slice layer contour range of the 3D model is completed.

[0012] Furthermore, in S1, the scanned and completely solidified set area of ​​the slice layer adjacent to the lower layer (limited to the "intersection area between the current layer contour and the upper layer contour that has been scanned") is a micro anchor point matrix. The micro anchor point matrix has a set number of slice layers to form a weak support structure. The micro anchor point matrix is ​​composed of multiple discrete contact points, which are sparsely distributed on its slice layer.

[0013] Furthermore, the plurality of contact points are distributed in a preset manner at all edge positions within the contour range of the slice layer, and in another preset manner in the non-edge regions within the contour range of the slice layer.

[0014] Furthermore, in S1, the slice layer identifying multiple heat conduction interconnection reference regions is the first layer of the 3D model, a specific weak connection layer, the first layer of the overhanging structure, or any intermediate layer that is prone to ineffective fusion.

[0015] Furthermore, S2 specifically includes:

[0016] S201. Establish a spatial rectangular coordinate system with the center point of the substrate as the origin;

[0017] S202. Divide the slice layer into a scanning dot matrix of a set density to obtain multiple scanning points of the slice layer and acquire multiple thermal conduction interconnection reference regions.

[0018] S203. Calculate the shortest distance from the scanning point to the range of the heat conduction connection reference area based on the coordinates of the scanning point, and use it as the heat conduction distance.

[0019] S204. Repeat step S203 with each heat conduction connection reference region as the reference to obtain multiple heat conduction distance sets with multiple heat conduction connection reference regions as the reference, wherein each heat conduction distance set corresponds to a unique heat conduction connection reference region.

[0020] Furthermore, in S3, the thermal connection distance threshold is greater than the distance between the centers of the two scanning points.

[0021] Furthermore, S4 specifically includes:

[0022] S401. Obtain the relative positions of multiple sets of points to be scanned, and sort them according to a set order to obtain a sorting table of multiple sets of points to be scanned.

[0023] S402. Obtain the thermal conduction distance value between each scan point in the set of points to be scanned and its corresponding thermal conduction connection reference area, and sort them according to the thermal conduction distance value from smallest to largest to obtain the internal sorting table of the set of points to be scanned.

[0024] S403. Control the laser to scan according to the set sorting table, and scan the set of points to be scanned in the set sorting table according to its internal sorting table.

[0025] S404. After the scan is completed, the set of points to be scanned is added to its corresponding thermal conduction interconnection reference region to form multiple new thermal conduction interconnection reference regions.

[0026] Furthermore, the slice layer is divided into multiple sectors, each sector is regarded as the outline range of the slice layer, and scanning is performed in each sector according to steps S2 to S5. Scanning is performed between multiple sectors in a set order.

[0027] This invention also provides a supportless printing system for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection, comprising:

[0028] The identification module is used to identify multiple thermal conduction interconnection reference regions within the contour range of the slice layer of the 3D model; wherein, the thermal conduction interconnection reference regions are the scanned and completely solidified areas of the slice layer immediately adjacent to the lower layer.

[0029] The calculation module is used to calculate the minimum Euclidean distance between all points to be scanned in the slice layer and all heat conduction interconnection reference regions as the heat conduction distance, and obtain multiple sets of heat conduction distances based on multiple heat conduction interconnection reference regions;

[0030] The filtering module is used to preset a thermal connectivity distance threshold and filter out a set of points to be scanned that are less than or equal to the thermal connectivity distance threshold from each set of thermal conduction distances, thereby obtaining multiple sets of points to be scanned.

[0031] The scanning module is used to control the laser to scan multiple sets of points to be scanned according to preset rules, and after the scanning is completed, the sets of points to be scanned are added to their corresponding heat conduction connection reference regions to form multiple new heat conduction connection reference regions.

[0032] The repeat module is used to repeat the steps of the calculation module and the scan module based on multiple new thermal conduction interconnection reference areas until the entire scan of the slice layer contour range of the 3D model is completed.

[0033] The beneficial effects of this invention are as follows:

[0034] 1. Improve process reliability: Based on the principle of absolute heat conduction connection, it fundamentally ensures metallurgical bonding and significantly reduces the incidence of non-fusion defects, especially in high-risk areas such as weak connection areas, the first layer, and the initial layer of the overhanging structure, thereby improving the stability of the molding process and the density of the parts.

[0035] 2. Achieving precise and controllable weak connections: By combining sparse micro-contact array design with low-energy scanning control based on thermal conduction, extremely weak connections between components and substrates or internal structures are achieved while ensuring necessary connection strength and molding stability. The separation force can be reduced by more than 90% compared to traditional strong connection methods, and the separation process is damage-free or with low damage.

[0036] 3. Enhanced resistance to thermal deformation: Active thermal management structures such as discrete heat dissipation rings can be used on the outer edge of 3D model parts. Combined with optimized scanning paths to guide symmetrical distribution of the thermal field and controllable heat input, thermal stress warping of large-sized thin-walled parts during the printing process is effectively suppressed, resulting in a flatness deviation of ≤0.1mm.

[0037] 4. It has strong versatility and scalability: Absolute thermal conductivity connection is independent of the specific scanning method (both point scanning and line scanning can be applied) and the application layer (first layer or any selected intermediate layer), with a wide range of protection. It can adapt to diverse weak connection needs (substrate connection, internal detachable structure, etc.) and improve the printing reliability of conventional structures.

[0038] 5. Excellent process compatibility: It is compatible with various mainstream LPBF metal powder materials (such as titanium alloy, aluminum alloy, stainless steel, high temperature alloy, etc.), and the parameter system (Power / Time for spot scanning, Power / Speed ​​for line scanning) is clear, making it easy to integrate into existing LPBF equipment and software, and has strong promotion potential. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection, as described in this invention.

[0040] Figure 2 This is a schematic diagram of the supportless printing system for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection, as described in this invention.

[0041] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0042] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0043] In LPBF (Laser Powder Bed Fusion) metal additive manufacturing, the following problems arise: 1. Uncontrollable connection strength between parts and the substrate or adjacent structures, making separation difficult; 2. Unsupported printing of large-scale, zero-angle overhanging surfaces; 3. Incomplete fusion defects caused by discontinuous or unstable heat conduction paths during the process, affecting molding stability; 4. Deformation due to thermal stress concentration in large-sized thin-walled parts or complex structures during LPBF printing. This invention provides an LPBF metal additive manufacturing method and system based on the principle of absolute thermal conduction connectivity, solving the above technical problems. It is particularly suitable for achieving controllable weak connections between parts and the substrate or internal structures, and improving the reliability and accuracy of the molding process.

[0044] This invention proposes and applies the principle of absolute thermal conductivity connectivity to the LPBF metal additive manufacturing process. During the scanning process of a selected layer (including but not limited to the first layer or any intermediate layer), through specific path planning and / or energy control strategies, it ensures that each molten pool forming in the current layer must establish a direct and effective thermal conduction channel with at least one fully solidified adjacent region (this region can be a scanned point / line in the same layer (the nth layer), or an adjacent solidified region in the (n-1)th layer) before solidification begins. The establishment of this thermal conduction channel is the physical basis for achieving metallurgical bonding and avoiding incomplete fusion defects, and it greatly reduces the number of supports required for heat transfer.

[0045] like Figure 1 As shown, this invention provides a supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity, comprising:

[0046] S1. Identify multiple thermal conduction interconnection reference regions within the contour range of the slice layer of the 3D model; wherein, the thermal conduction interconnection reference regions are the scanned and completely solidified regions of the slice layer immediately adjacent to the lower layer.

[0047] Specifically as follows:

[0048] The area immediately adjacent to the scanned and completely solidified region of the sliced ​​layer (limited to the intersection of the current layer contour and the scanned previous layer contour) is the top of the micro-anchor lattice. This micro-anchor lattice structure is used for weak connections; that is, a micro-contact array structure is designed at the bottom of the target component that needs to form a weak connection with the substrate. This structure consists of multiple discrete small-sized contact points. The contact points of a predetermined number of sliced ​​layers can form contact pillars, i.e., three-dimensional shapes such as cylinders and frustums. These shapes form the contact array structure of the weak connection portion. After printing, applying a slight mechanical force or thermal shock (such as localized heating / cooling) to the component with the micro-contact array structure achieves non-destructive or low-damage separation of the component from the substrate, with no or minimal residue at the connection point.

[0049] Multiple contact points are sparsely distributed on its slice layer, and multiple contact points are preset according to the lower surface or suspended surface of the part to be printed. The contact points must be distributed at the edge position, and the other positions are distributed according to the rules. After the contact point array is printed through 10 to 50 slice layers, it forms a contact array structure of the weak connection part.

[0050] In addition, during the printing process, an active heat dissipation structure can be set at the outer edge of the slice layer contour range, such as a discrete heat dissipation ring around the outer edge of the part, which is composed of multiple independent arcs, to guide the thermal field and reduce thermal stress concentration.

[0051] As described above, the region is defined as the layer or region where the principle of absolute thermal conductivity connectivity needs to be applied. This can be the first layer of a 3D model, a specific weakly connected layer, the first layer of a suspended structure, or any intermediate layer prone to ineffective fusion. Next, a scanning path is generated for the selected slice layer, and a sorting algorithm is applied, as shown in steps S2-S5 below. This ensures that before energy input, the geometric position of each point to be melted (point scan mode) or line segment (line scan mode) on the scanning path must satisfy a preset spatial proximity condition with at least one predetermined solidified reference region, such as point spacing ≤ effective thermal conductivity distance threshold. This threshold is related to the material's thermal properties and process parameters. Simultaneously, the scanning sequence must ensure that when the current point / line melts, the solidified reference region establishing a thermal conductivity channel with it must be in a fully solidified state.

[0052] S2. Calculate the minimum Euclidean distance between all points to be scanned in the slice layer and all thermal conduction interconnection reference regions as the thermal conduction distance, and obtain multiple sets of thermal conduction distances based on multiple thermal conduction interconnection reference regions.

[0053] S201. Establish a spatial rectangular coordinate system with the center point of the substrate as the origin;

[0054] S202. Divide the slice layer into a scanning dot matrix of a set density to obtain multiple scanning points of the slice layer and acquire multiple thermal conduction interconnection reference regions.

[0055] S203. Calculate the shortest distance from the scanning point to the range of the heat conduction connection reference area based on the coordinates of the scanning point, and use it as the heat conduction distance.

[0056] As described in steps S202-S203, in a fixed rectangular coordinate system, the coordinates of each scanning point are fixed, and the circumferential coordinates of each heat conduction connection reference area are also fixed. That is, the distance from the scanning point to the heat conduction connection reference area can be calculated. This distance will have multiple distances due to different connecting lines. The shortest distance among the multiple distances is selected as the heat conduction distance from the scanning point to the heat conduction connection reference area.

[0057] S204. Repeat step S203 with each heat conduction connection reference region as the reference to obtain multiple heat conduction distance sets with multiple heat conduction connection reference regions as the reference, wherein each heat conduction distance set corresponds to a unique heat conduction connection reference region.

[0058] That is, the distance between each heat conduction connection reference region and each scan is calculated, resulting in a set of heat conduction distances for each heat conduction connection reference region.

[0059] S3. Preset a thermal connection distance threshold, and select a set of points to be scanned that are less than or equal to the thermal connection distance threshold from each set of thermal conduction distances, thereby obtaining multiple sets of points to be scanned.

[0060] The thermal connection distance threshold is greater than the distance between two scanning points, so that the point to be scanned can make contact with the reference point after the scanning is completed.

[0061] S4. Control the laser to scan multiple sets of points to be scanned according to preset rules, and after the scanning is completed, add the sets of points to be scanned to their corresponding thermal conduction interconnection reference regions to form multiple new thermal conduction interconnection reference regions.

[0062] S401. Obtain the relative positions of multiple sets of points to be scanned, and sort them according to a set order to obtain a sorting table of multiple sets of points to be scanned; in addition, when the scanning mode is line scan, the multiple points to be scanned are the starting points of the line segments in the line scan.

[0063] S402. Obtain the thermal conduction distance value between each scan point in the set of points to be scanned and its corresponding thermal conduction connection reference area, and sort them according to the thermal conduction distance value from smallest to largest to obtain the internal sorting table of the set of points to be scanned. The closer the scan point is to the reference point, the more stable the scanned structure can be by scanning according to the order of the internal sorting table.

[0064] S403. Control the laser to scan according to the set sorting table, and scan the set of points to be scanned in the set sorting table according to its internal sorting table.

[0065] S404. After the scan is completed, the set of points to be scanned is added to its corresponding thermal conduction interconnection reference region to form multiple new thermal conduction interconnection reference regions.

[0066] After each point / line segment is scanned and confirmed to have solidified, it is added to the solidified reference region (i.e., the thermal conduction connectivity reference region) for subsequent point / line sorting and scanning. Regardless of the method used, the final scanning order must satisfy the principle of absolute thermal conduction connectivity, that is, when each new molten pool melts, its location must have at least one solidified and spatially adjacent reference region that can provide an effective thermal conduction and heat dissipation path.

[0067] S5. Repeat steps S2 to S4 based on multiple new heat conduction connection reference regions until the entire scan of the slice layer contour range of the 3D model is completed.

[0068] In addition, the slice layer that needs to be scanned can be divided into multiple sectors. Each sector is regarded as the outline range of the slice layer and scanned in each sector according to steps S2 to S5. The multiple sectors are scanned in a set order (such as clockwise or counterclockwise) to balance the thermal field distribution.

[0069] During the scanning process, an energy control strategy is employed, using energy control parameters that match the selected scanning mode (point or line). The core parameters for point scanning are laser power and exposure time, precisely controlling the energy input at a single point. The core parameters for line scanning are laser power and scanning speed, or an equivalent energy density control method. Simultaneously, different energy parameters (such as power and time / speed) can be set for micro-contact areas (e.g., micro-anchor layers), the main body area, and heat dissipation structure areas to optimize fusion quality and thermal management. For example, the micro-anchor layer can use relatively high energy to ensure fusion with the substrate, while the weakly connected main body layer uses lower energy input.

[0070] The specific 3D printing process is as follows:

[0071] (1) Set the forming substrate on the liftable printing platform and level it.

[0072] (2) High-purity Ar (Argon) gas is introduced into the laser forming chamber as a protective atmosphere to maintain a safe oxygen content.

[0073] (3) The printing equipment is operated to print layer by layer according to the path planning and set energy parameters generated based on the principle of absolute thermal conduction interconnection. For example, let's take printing an Inconel 718 thin-walled disk on a substrate with weak connections as an example:

[0074] a) Design: Cylindrical micro-anchor points are designed on the outer edge of the bottom of the disk, and cylindrical micro-anchor points are also set in the non-edge areas. The radial and circumferential spacing of the cylindrical micro-anchor points are preset according to rules. An independent heat dissipation ring is designed on the outer edge of the disk.

[0075] b) Substrate and atmosphere: The substrate is preheated and the protective atmosphere is Ar.

[0076] c) Path and Energy (Application of Absolute Thermal Conductivity Connection Principle): The micro-anchor layer is considered as a solidified reference region (thermal conductivity connection reference region) and can be generated using traditional vector scanning to ensure fusion. The first layer of the disk is the layer applying the core principle (the micro-contact array structure below the first layer is the weakly connected part). The center point of the top surface of the micro-anchor pillars of the first layer of the disk is defined as the solidified reference region (thermal conductivity connection reference region). The first layer of the disk is divided into multiple sectors. Using a point scanning mode, the distance from each point on the first layer of the disk to the center reference point of each micro-anchor is calculated. Points with a distance ≤ thermal connectivity threshold are selected. Within each sector, the point closest to the nearest reference point is scanned first. The scanning between sectors is in a clockwise order to ensure that when each new point melts, at least one reference point (the top of the micro-anchor) has solidified and is close enough.

[0077] d) Subsequent layers and heat dissipation rings: This principle can continue to be applied or other optimization strategies can be adopted. The heat dissipation rings can use similar or different parameters.

[0078] (4) After printing, apply slight mechanical force or thermal shock (such as local heating / cooling) to the parts with micro-contact array structure to achieve non-destructive or low-damage separation of the parts from the substrate, with no or minimal residue at the connection.

[0079] In this invention, the substrate material is a commonly used forming substrate material, such as 316L stainless steel, mold steel (e.g., H13), titanium alloy (e.g., TC4), nickel-based alloy (e.g., Inconel 718), etc. The optimal choice depends on the printing material (requiring matching coefficients of thermal expansion and good solderability). For example, for printing titanium alloy parts, a TC4 substrate is preferred; for printing stainless steel, a 316L or mold steel substrate is preferred. A wide range of LPBF metal powders are suitable for printing, including but not limited to:

[0080] 1) Optimal commonly used materials: 316L stainless steel (good fluidity, mature process), Ti6Al4V(TC4) titanium alloy (lightweight and high strength, biocompatible), AlSi10Mg aluminum alloy (lightweight).

[0081] 2) Other applicable materials: Inconel 718 nickel-based high-temperature alloy (high temperature resistance), CoCrMo cobalt-chromium alloy (biomedical), CuCrZr copper alloy (high thermal conductivity), 18Ni300 mold steel, high-strength steel, etc.

[0082] 3) Key to Material Replacement: The "thermal communication distance threshold" and energy parameters (Power, Time / Speed) need to be adjusted according to the specific material. The threshold may be larger for high thermal conductivity materials (such as Cu), while the threshold is smaller for high melting point / low thermal conductivity materials (such as high-temperature alloys), and the energy requirements are higher. Specific parameters need to be calibrated experimentally.

[0083] In summary, this invention employs the principle of absolute thermal conductivity connectivity. During LPBF layer scanning, the scanning path and / or sequence are controlled to ensure that when the current point / line molten pool is formed, its position establishes a direct and effective thermal conductivity channel with at least one fully solidified adjacent region (a solidified point / line in the same layer or a solidified region immediately below layer N-1). The solidified region must be in a fully solidified state. The condition for establishing a thermal conductivity channel is that the Euclidean distance between the molten pool position and the solidified region is ≤ a preset thermal connectivity distance threshold (this threshold is determined by the material's thermal properties and process parameters).

[0084] For the path planning method, the solidified reference regions on the selected layer (solidified points at specific locations in the lower layer (n-1 layer)) are identified. A scanning path is generated for the selected layer, and a sorting algorithm is applied to ensure that each point / line to be scanned satisfies the spatial proximity condition (≤ thermal connectivity threshold) with at least one solidified reference region. The scanning order must ensure that when the current point / line melts, its associated solidified reference region is in a fully solidified state. Various implementation methods are available, including but not limited to sorting by ascending distance to the nearest reference point, sorting by the number of reference points, sector-based sorting (sorting within a sector according to rules, and traversing between sectors according to a predetermined rule), and dynamically updating the reference point set.

[0085] Employing a weakly connected structural design in conjunction with the principle of absolute heat conduction, this design utilizes a micro-contact array structure and an active cooling structure. The micro-contact array consists of multiple discrete, small-sized contact points / pillars sparsely distributed across the contact surface. The active cooling structure is a segmented heat dissipation ring surrounding the component, without direct fusion with the main body, used for directional heat dissipation and balancing the thermal field.

[0086] Furthermore, this invention employs an energy control strategy adapted to the principle of absolute thermal conduction interconnection and weak connections. Specifically, the point scanning mode uses a combination of laser power and exposure time; the line scanning mode uses a combination of laser power and scanning speed. Different energy parameters are set for the micro-contact area (such as the anchor layer) and the main weak connection area (such as the first layer) (e.g., higher energy for the micro-contact area and lower energy for the weak connection main area).

[0087] This invention can be applied in multiple fields, as described below:

[0088] 1. Aerospace field. Application methods: rapid engine blade testing (printing blades with weak connections, non-destructive separation testing); lightweight structure verification (printing large-size thin-walled parts with weak connections, such as wing skin). Technical advantages: reduced separation damage, improved testing efficiency and data accuracy, and lower post-processing costs.

[0089] 2. Medical Device Manufacturing. Applications: Separable orthopedic implants (titanium alloy bone nails / plates with weak connection, allowing for minimal postoperative separation); biocompatible scaffolds (weakly connected printed vascular scaffolds, avoiding cutting burrs). Technological Advantages: "Print-on-demand" integrated manufacturing avoids surface defects caused by the supporting structure, reducing trauma from secondary surgeries.

[0090] 3. Precision electronic components. Applications: Microelectromechanical systems (MEMS) heat sinks (using segmented heat dissipation rings to print high-precision copper alloy heat sinks); flexible circuit carriers (printing ultra-thin metal substrates ≤0.5mm with weak connections). Technical advantages: Solves the problem of thermal deformation during the printing of thin-walled components, improving yield and thermal management performance.

[0091] 4. Automotive Industry. Applications: Fuel injector performance testing (weakly connected printed nozzle prototypes for rapid separation testing); lightweight body parts (rapid prototyping of aluminum alloy hinges, etc.). Technical Advantages: One-time molding and non-destructive disassembly of complex structures, shortening the R&D cycle and reducing prototyping costs.

[0092] 5. Scientific Research and Education. Applications: Materials research specimens (printing samples with different weak bonding parameters to study bonding strength and thermal deformation); additive manufacturing teaching models (demonstrating the principles of weak bonding and heat conduction control). Technical Advantages: Providing standardized weak bonding samples to promote fundamental research in metal additive manufacturing processes.

[0093] 6. Energy Sector. Applications: Fuel cell bipolar plates (weakly connected printed stainless steel bipolar plates); nuclear reactor micro-components (precision manufacturing of zirconium alloy fuel assembly support grids). Technical Advantages: Adapts to the requirements of weak connections in highly corrosion-resistant materials, improving component reliability and manufacturing precision.

[0094] 7. Mold and Tool Manufacturing. Applications: Conformal cooling molds (printing mold inserts with weak connections for easy and quick replacement); micro-injection nozzles (printing metal nozzles with weak connections and a diameter ≤1mm). Technical Advantages: Shortens mold iteration cycle, solves the problem of separating micro-structures, and avoids post-processing breakage.

[0095] Potential derivative technologies include: 1) Multi-material weak bonding: extending to additive manufacturing of weak bonding between ceramics and metals or dissimilar metals. 2) Intelligent separation system: integrating temperature / stress sensors to achieve online monitoring and active control of bonding strength. 3) Cross-scale applications: applying core principles to micro / nano-scale LPBF or electron beam melting (EBM) processes. 4) Software modularization: developing a dedicated LPBF slicing software module integrating an "absolute thermal conduction connectivity path planning algorithm." 5) Microgravity environment adaptation: optimizing weak bonding design and thermal conduction control strategies for the space 3D printing environment.

[0096] like Figure 2 As shown, the present invention also provides a supportless printing system for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection, comprising:

[0097] The identification module 1 is used to identify multiple thermal conduction interconnection reference regions within the contour range of the slice layer of the 3D model; wherein, the thermal conduction interconnection reference region is a scanned and completely solidified region adjacent to the lower layer of the slice layer, or a scanned and solidified region in the slice layer.

[0098] Calculation module 2 is used to calculate the minimum Euclidean distance between all points to be scanned in the slice layer and all heat conduction interconnection reference regions as the heat conduction distance, and obtain multiple sets of heat conduction distances based on multiple heat conduction interconnection reference regions;

[0099] The filtering module 3 is used to preset the thermal connection distance threshold and filter out the set of points to be scanned that are less than or equal to the thermal connection distance threshold in each set of thermal conduction distances, so as to obtain multiple sets of points to be scanned.

[0100] The scanning module 4 is used to control the laser to scan multiple sets of points to be scanned according to preset rules, and after the scanning is completed, the sets of points to be scanned are added to their corresponding heat conduction connection reference regions to form multiple new heat conduction connection reference regions.

[0101] Repeat module 5 is used to repeat the steps of the calculation module ~ scan module according to multiple new thermal conduction connection reference areas until the entire scan of the slice layer contour range of the 3D model is completed.

[0102] Each of the above modules is applicable to the corresponding execution of each step in the LPBF metal additive manufacturing unsupported printing method based on absolute thermal conductivity. The specific implementation method is as described in the above method embodiments, and will not be repeated here.

[0103] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0104] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection, characterized in that, include: S1. Identify multiple thermal conduction interconnection reference regions within the contour range of the slice layer of the 3D model; wherein, the thermal conduction interconnection reference region is a scanned and completely solidified region adjacent to the lower layer of the slice layer; the scanned and completely solidified region adjacent to the lower layer of the slice layer is a micro-anchor lattice, the micro-anchor lattice has a set number of slice layers to form a weak support structure; the micro-anchor lattice is composed of multiple discrete contact points, and the multiple contact points are sparsely distributed on its slice layer; S2. Calculate the minimum Euclidean distance between all points to be scanned in the slice layer and all thermal conduction interconnection reference regions as the thermal conduction distance, and obtain multiple sets of thermal conduction distances based on multiple thermal conduction interconnection reference regions; S3. A preset thermal connectivity distance threshold is set, and a set of points to be scanned that are less than or equal to the thermal connectivity distance threshold is selected from each set of thermal conduction distances to obtain multiple sets of points to be scanned; wherein, the thermal connectivity distance threshold is greater than the distance between two scanned points; S4. Control the laser to scan multiple sets of points to be scanned according to preset rules, and after the scanning is completed, add the sets of points to be scanned to their corresponding heat conduction connection reference regions to form multiple new heat conduction connection reference regions. S5. Repeat steps S2 to S4 based on multiple new heat conduction connection reference regions until the entire scan of the slice layer contour range of the 3D model is completed.

2. The supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity as described in claim 1, characterized in that, The multiple contact points are distributed in a preset manner at all edge positions within the contour range of the slice layer, and in another preset manner in the non-edge areas within the contour range of the slice layer.

3. The supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity as described in claim 1, characterized in that, In S1, the slice layer that identifies multiple heat conduction interconnection reference regions is the first layer of the 3D model, a specific weak connection layer, the first layer of the overhanging structure, or any intermediate layer that is prone to ineffective fusion.

4. The supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity as described in claim 1, characterized in that, S2 specifically includes: S201. Establish a spatial rectangular coordinate system with the center point of the substrate as the origin; S202. Divide the slice layer into a scanning dot matrix of a set density to obtain multiple scanning points of the slice layer and acquire multiple thermal conduction interconnection reference regions. S203. Calculate the shortest distance from the scanning point to the range of the heat conduction connection reference area based on the coordinates of the scanning point, and use it as the heat conduction distance. S204. Repeat step S203 with each heat conduction connection reference region as the reference to obtain multiple heat conduction distance sets with multiple heat conduction connection reference regions as the reference, wherein each heat conduction distance set corresponds to a unique heat conduction connection reference region.

5. The supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity as described in claim 1, characterized in that, S4 specifically includes: S401. Obtain the relative positions of multiple sets of points to be scanned, and sort them according to a set order to obtain a sorting table of multiple sets of points to be scanned. S402. Obtain the thermal conduction distance value between each scan point in the set of points to be scanned and its corresponding thermal conduction connection reference area, and sort them according to the thermal conduction distance value from smallest to largest to obtain the internal sorting table of the set of points to be scanned. S403. Control the laser to scan according to the set sorting table, and scan the set of points to be scanned in the set sorting table according to its internal sorting table. S404. After the scan is completed, the set of points to be scanned is added to its corresponding thermal conduction interconnection reference region to form multiple new thermal conduction interconnection reference regions.

6. The supportless printing method for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection according to claim 5, characterized in that, The slice layer is divided into multiple sectors. Each sector is considered as the outline range of the slice layer and is scanned in each sector according to steps S2 to S5. The multiple sectors are scanned in a set order.

7. A supportless printing system for LPBF metal additive manufacturing based on absolute thermal conductivity interconnection, characterized in that, include: The identification module is used to identify multiple thermal conduction interconnection reference regions within the contour range of a slice layer of a 3D model; wherein, the thermal conduction interconnection reference region is a scanned and completely solidified region immediately adjacent to the lower layer of the slice layer; the scanned and completely solidified region immediately adjacent to the lower layer of the slice layer is a micro-anchor lattice, the micro-anchor lattice having a predetermined number of slice layers to form a weak support structure; the micro-anchor lattice is composed of multiple discrete contact points, which are sparsely distributed on its slice layer; The calculation module is used to calculate the minimum Euclidean distance between all points to be scanned in the slice layer and all heat conduction interconnection reference regions as the heat conduction distance, and obtain multiple sets of heat conduction distances based on multiple heat conduction interconnection reference regions; A filtering module is used to preset a thermal connectivity distance threshold and filter out a set of points to be scanned that are less than or equal to the thermal connectivity distance threshold from each set of thermal conduction distances, thereby obtaining multiple sets of points to be scanned; wherein, the thermal connectivity distance threshold is greater than the distance between two scanned points; The scanning module is used to control the laser to scan multiple sets of points to be scanned according to preset rules, and after the scanning is completed, the sets of points to be scanned are added to their corresponding heat conduction connection reference regions to form multiple new heat conduction connection reference regions. The repeat module is used to repeat the steps of the calculation module and the scan module based on multiple new thermal conduction interconnection reference areas until the entire scan of the slice layer contour range of the 3D model is completed.

Images