LPBF metal additive manufacturing path planning method and system based on thermal stress interlayer active release mechanism

Abstract

The invention relates to the technical field of metal 3D printing, and discloses an LPBF metal additive manufacturing path planning method and system based on a thermal stress interlayer active release mechanism, and the method comprises the steps: setting a stress release region as a target slice layer in a slice layer contour range of a 3D model; acquiring a plurality of partitions for realizing a stress release function in a target slice contour layer range, and planning a scanning path for each partition; controlling the laser to scan each subarea according to the corresponding scanning path, and randomly skipping in a plurality of adjacent subareas until scanning of all subareas is completed; the next slice layer is converted to serve as a new target slice layer, a stress release area similar to the original target slice layer is arranged on the new target slice layer, and interlayer dislocation design is adopted for the new stress release area and the original stress release area; and repeatedly scanning and skipping to the next slice layer until scanning of all slice layers in the whole 3D model is completed. By designing the controllable stress release structure, stage reduction of thermal stress is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal 3D printing, in particular to a LPBF metal additive manufacturing path planning method and system based on a thermal stress interlayer active release mechanism. BACKGROUND

[0002] In the field of additive manufacturing technology, the laser powder bed fusion (LPBF) process is widely used in high-end manufacturing due to its high precision and complex structure forming advantages. However, the generation and accumulation of thermal stress in this process can cause part deformation, residual stress retention and other problems. The scientific nature of the scanning path directly determines the thermal stress distribution, printing efficiency and part forming quality. Therefore, related optimization techniques have become the core of industry research.

[0003] Although there are currently several related technical solutions, there are still obvious limitations in practical application. For example: ① By dividing the work platform and part slice data into grid regions, randomly selecting regions and scanning along a specific angle to optimize the stress timing; it uses simple rectangular grid division, which cannot provide more uniform heat distribution, and lacks a special stress release mechanism design, relying only on random scanning order to optimize stress travel timing, which cannot achieve stress release; the jump scanning strategy between regions can lead to uneven heat accumulation. ② Relying on a database and a Gaussian process proxy model, combining finite element analysis and model training to optimize 3D printing paths and reduce part deformation. It relies on complex finite element analysis and model training, which has high computational cost; it lacks a physical level stress release design and relies entirely on algorithm optimization; the grid division is fixed and does not consider the rotation changes between multiple layers; the path planning lacks a jump mechanism. ③ For high-melting-point thin-walled parts, the scanning line is segmented and scanned in a preset interval order to adapt to the material forming characteristics. Although it uses segmented scanning, it does not have a clear stress release structure design; the division and order of scanning segments mainly consider temperature gradients rather than systematic stress management.

[0004] In summary, in current LPBF metal additive manufacturing, passive uniformization of thermal stress distribution is achieved only by scanning order optimization, which cannot achieve active reduction of thermal stress, leading to stress concentration in the edge area causing warping deformation, multiple layers of fixed partition boundaries forming a penetrating stress concentration line, and Z-direction stress accumulation leading to structural failure risk. These problems directly restrict the further promotion and application of the LPBF process in high-precision and high-reliability part manufacturing. SUMMARY

[0005] The present application provides a LPBF metal additive manufacturing path planning method and system based on a thermal stress interlayer active release mechanism, which achieves phased reduction of thermal stress by designing a controllable stress release structure.

[0006] This invention provides a path planning method for LPBF metal additive manufacturing based on an active interlayer thermal stress release mechanism, comprising: S1. Set one or more stress relief regions within the outline of the slice layer of the 3D model, and use them as the target slice layer; wherein, the stress relief region is a weak scan region or a non-scan region; S2. Obtain multiple partitions of the target slice layer contour range by which the stress relief region is divided, and plan the scanning path for each partition. S3. Control the laser to scan each partition according to its corresponding scanning path, and after completing the scanning of a target partition, take the adjacent partitions of the target partition as new target partitions for scanning, until the scanning of all partitions of the target slice layer is completed. S4. Switch to the next slice layer of the 3D model and use it as the new target slice layer. Set a stress release area in the new target slice layer that is similar to the original target slice layer, and the new stress release area and the original stress release area adopt an interlayer misalignment design. S5. Repeat steps S2 to S4 until all slice layers in the entire 3D model have been scanned.

[0007] Furthermore, in the scanning of the stress relief area, the laser energy density used is 0-40% of the ordinary laser energy density, where the ordinary laser energy density is the laser energy density used to scan multiple zones; When the laser energy density is 0% of the ordinary laser energy density, the stress release area is a non-scanning area; when the laser energy density is any of the remaining values, the stress release area is a weakly scanned area.

[0008] Furthermore, the stress relief area is 5-15% of the total area of ​​the target slice layer.

[0009] Furthermore, the stress relief area is configured as a seam type, a cavity type, or a polygonal boundary type; The seam type is to set a continuous seam strip of a set width at each partition boundary, that is, to divide the outline range of the target slice layer into multiple partitions by a continuous line segment of a set width; The cavity type is obtained by setting a circular or polygonal non-scanning area as a cavity inside each partition after obtaining multiple partitions. The polygonal boundary method is to divide the outline of the target slice layer into an arbitrary number of polygons, and the edges of the polygons serve as the stress relief areas.

[0010] Furthermore, in the target slice layer, each partition forms an independent region, and each partition has the same shape or the same area.

[0011] Furthermore, the stress relief region in the target slice layer is taken as the target stress relief region, and the stress relief region in the slice layer adjacent to the target slice layer is taken as the adjacent stress relief region. The target stress relief region is rotated by a set angle with the center point of the target slice layer as a reference to obtain the adjacent stress relief region.

[0012] Furthermore, in the 3D model, the rotation angle of the stress relief area varies randomly between every two slice layers.

[0013] Furthermore, the stress relief region in the target slice layer is taken as the target stress relief region, and the stress relief region in the slice layer adjacent to the target slice layer is taken as the adjacent stress relief region. The target stress relief region is translated by a set distance to obtain the adjacent stress relief region; wherein, the set distance is ≥ 50% of the width of the stress relief region.

[0014] Furthermore, the scan path for each partition in the target slice layer is a random or linear scan path.

[0015] This invention also provides an LPBF metal additive manufacturing path planning system based on an active interlayer thermal stress release mechanism, comprising: The setting module is used to set one or more stress relief regions within the outline of a slice layer of a 3D model, and to serve as the target slice layer; wherein, the stress relief region is a weakly scanned region or a non-scanned region; The acquisition module is used to acquire multiple partitions of the stress relief region in relation to the contour range of the target slice layer, and to plan a scanning path for each partition. The control module is used to control the laser to scan each partition according to its corresponding scanning path, and after completing the scanning of a target partition, to scan the adjacent partitions of the target partition as new target partitions, until the scanning of all partitions of the target slice layer is completed. The conversion module is used to convert to the next slice layer of the 3D model and use it as the new target slice layer. The new target slice layer sets a stress relief area similar to the original target slice layer, and the new stress relief area and the original stress relief area adopt an interlayer misalignment design. The loop module is used to repeat steps S2 to S4 until all slice layers in the entire 3D model have been scanned.

[0016] The beneficial effects of this invention are as follows: 1. Set up an active thermal stress release mechanism, that is, set up multiple non-scanning areas or scanned areas in each slice layer of the 3D model, which can reduce the total residual stress by 40-60% and the edge deformation by 60-80%, so that the flatness of thin-walled parts is ≤0.05mm / m.

[0017] 2. Achieves breakthroughs in process compatibility, applicable to any scanning method (vector / point scanning) and any partitioning form (cellular / rectangular / custom polygon), while also supporting multi-material systems, and widening the process window by 30%.

[0018] 3. Achieve synergistic optimization of efficiency and quality by adopting partitioned migration scanning, which involves scanning multiple partitions composed of multiple stress relief areas one by one, thereby reducing idle time by 15% and ensuring that the proportion of stress relief structures is ≤15% and the rate of non-fusion defects is <0.3%. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism of the present invention.

[0020] Figure 2 This is a schematic diagram of the LPBF metal additive manufacturing path planning system based on the active interlayer release mechanism of thermal stress according to the present invention.

[0021] 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

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0023] In the traditional LPBF (Laser Powder Bed Fusion) process, thermal stress is passively homogenized rather than actively released. The edge deformation caused by residual stress leads to the superposition of interlayer stress, and the fixed partition boundary forms a stress concentration line. Uneven heat accumulation along the scanning path results in low printing efficiency.

[0024] This invention proposes an active interlayer thermal stress release mechanism. It pre-sets controllable stress release structures (including but not limited to seams, cavities, or polygonal boundaries) within the layers, uses a partitioned migration scanning strategy to block the thermal stress propagation path, and avoids stress superposition through multi-layer dynamic misalignment design, ultimately achieving phased reduction of thermal stress.

[0025] like Figure 1 As shown, this invention provides a path planning method for LPBF metal additive manufacturing based on an active interlayer thermal stress release mechanism, comprising: S1. Set one or more stress relief regions within the outline of the slice layer of the 3D model, and use them as the target slice layer; wherein, the stress relief region is a weak scan region or a non-scan region.

[0026] During the scanning of the stress relief region, the laser energy density used is 0-40% of the ordinary laser energy density, where the ordinary laser energy density is the laser energy density used to scan multiple zones. When the laser energy density is 0% of the ordinary laser energy density, the stress relief region is a non-scanning region; when the laser energy density is any of the remaining values, the stress relief region is a weakly scanned region. Ultimately, the stress relief region is 5-15% of the total area of ​​the target slice layer.

[0027] In one embodiment, the stress relief area is configured as a seam type, a cavity type, or a polygonal boundary type.

[0028] (1) Seam type: Set a continuous seam strip of a set width at each partition boundary (such as a hexagonal honeycomb edge), that is, divide the target slice layer outline range into multiple partitions by a continuous line segment of a set width.

[0029] (2) Cavity type: After obtaining multiple partitions, a circular or polygonal non-scanning area is set inside each partition as a cavity. The cavity area can be used as a further stress release area for the joint type. The cavity area is not scanned.

[0030] (3) Polygonal boundary type: The outline of the target slice layer is divided into any number of polygons (such as rectangles and triangles). The edges of the polygons are used as the stress release areas. Similarly, based on the polygonal boundary type, a cavity-type non-scanning area can also be set to further release stress.

[0031] The various settings for stress relief zones described above can actively block heat conduction paths during scanning, allowing residual stress to be released in stages within the layer, rather than being uniformly distributed.

[0032] S2. Obtain multiple partitions of the target slice layer contour range by which the stress relief region is divided, and plan the scanning path for each partition.

[0033] (1) Set the target slice layer partition In the target slice layer, each partition forms an independent region (such as a hexagon, rectangle, or triangle).

[0034] (2) Set up partition transformation strategy for adjacent slice layers a. Rotation: The stress relief region in the target slice layer is taken as the target stress relief region, and the stress relief region in the slice layer adjacent to the target slice layer is taken as the adjacent stress relief region. The target stress relief region is rotated by a set angle with the center point of the target slice layer as a reference to obtain the adjacent stress relief region. The rotation angle of the stress relief region between each two slice layers changes randomly (that is, the adjacent slice layer can rotate clockwise or counterclockwise with respect to the target slice layer with the center point as a reference, and the rotation angle is any angle that ensures that the stress relief regions of the adjacent layers are staggered).

[0035] b. Translation: The stress release area in the target slice layer is taken as the target stress release area, and the stress release area in the slice layer adjacent to the target slice layer is taken as the adjacent stress release area. The target stress release area is translated by a set distance to obtain the adjacent stress release area.

[0036] By employing an interlayer staggered design, stress propagation channels are prevented from running through each other, and combined with partitioned migration scanning, three-dimensional stress reduction is achieved, thus blocking stress in the Z direction.

[0037] S3. Control the laser to scan each partition according to its corresponding scanning path, and after completing the scanning of a target partition, scan the adjacent partitions of the target partition as new target partitions, until the scanning of all partitions of the target slice layer is completed.

[0038] The scanning path for each partition in the target slice layer can be random or linear, and can be set by a preset algorithm or planned manually.

[0039] Within the partition of the target slice layer, scanning is performed using arbitrary scanning paths such as random or linear. After completing a set number of point scans (laser scanning can be performed using point or line scanning), the system randomly jumps to an adjacent partition for scanning.

[0040] S4. Switch to the next slice layer of the 3D model and use it as the new target slice layer. Set a stress release area in the new target slice layer that is similar to the original target slice layer, and the new stress release area and the original stress release area adopt an interlayer misalignment design.

[0041] S5. Repeat steps S2 to S4 until all slice layers in the entire 3D model have been scanned.

[0042] In this invention, the area ratio of the stress relief region is used to control the thermal stress reduction efficiency, the partition migration jump setting is used for heat accumulation control, and the interlayer misalignment setting is used to control the Z-axis stress blocking effect; its parameters can be dynamically adjusted according to the thermal expansion coefficient of the material (e.g., increasing the joint width for titanium alloys and increasing the jump frequency for high-temperature alloys). For example, high-strength alloys (such as 718) adopt a cavity-type stress relief structure, thin-walled parts (such as Al alloys) adopt a joint-type stress relief structure, and large-size components adopt a polygonal boundary-type stress relief structure.

[0043] This invention actively blocks heat conduction paths by pre-setting non-scanning or weak-scanning stress relief structures (seams / cavities / boundaries). These stress relief structures occupy 5-15% of the target slice layer area, and their position and shape are programmable. After completing the set zonal scanning, it jumps to a randomly selected adjacent zonal, with the jump threshold dynamically matched to the material's thermophysical properties. Multi-layer dynamic misalignment control is employed, with the inter-layer stress relief structure misalignment ≥50% of the width of the stress relief area, and the rotation angle of adjacent slice layer zonals changing randomly. The final technical effects achieved are as follows: 1. Active thermal stress release: By setting multiple non-scanning or semi-scanning areas in each slice layer of the 3D model, the total residual stress can be reduced by 40-60%, while the edge deformation is reduced by 60-80%, resulting in a flatness of thin-walled parts ≤0.05mm / m.

[0044] 2. Achieves breakthroughs in process compatibility, applicable to any scanning method (vector / point scanning) and any partitioning form (cellular / rectangular / custom polygon), while also supporting multi-material systems, and widening the process window by 30%.

[0045] 3. Achieve synergistic optimization of efficiency and quality by adopting partitioned migration scanning, which involves scanning multiple partitions composed of multiple stress relief areas one by one, thereby reducing idle time by 15% and ensuring that the proportion of stress relief structures is ≤15% and the rate of non-fusion defects is <0.3%.

[0046] This invention also provides an LPBF metal additive manufacturing path planning system based on an active interlayer thermal stress release mechanism, comprising: The setting module is used to set one or more stress relief regions within the outline of a slice layer of a 3D model, and to serve as the target slice layer; wherein, the stress relief region is a weakly scanned region or a non-scanned region; The acquisition module is used to acquire multiple partitions of the stress relief region in relation to the contour range of the target slice layer, and to plan a scanning path for each partition. The control module is used to control the laser to scan each partition according to its corresponding scanning path, and after completing the scanning of a target partition, to scan the adjacent partitions of the target partition as new target partitions, until the scanning of all partitions of the target slice layer is completed. The conversion module is used to convert to the next slice layer of the 3D model and use it as the new target slice layer. The new target slice layer sets a stress relief area similar to the original target slice layer, and the new stress relief area and the original stress relief area adopt an interlayer misalignment design. The loop module is used to repeat steps S2 to S4 until all slice layers in the entire 3D model have been scanned.

[0047] Each of the above modules is used to execute the steps in the LPBF metal additive manufacturing path planning method based on the active release mechanism of interlayer thermal stress. The specific implementation method is as described in the above method embodiment, and will not be repeated here.

[0048] This invention has several applications in aerospace, including turbine blade edge deformation prevention and lightweight satellite support manufacturing, reducing residual stress by 60% and preventing Z-axis fracture. In medical devices, it improves structural integrity and reduces post-processing costs by 40% in low-stress printing of porous implants and biodegradable magnesium alloy scaffolds. In energy equipment, it enhances corrosion resistance and thermal fatigue life in fuel cell bipolar plate channels and zirconium alloy components for nuclear reactors. In precision electronics, it improves dimensional accuracy to ±0.02mm in MEMS copper alloy heat sinks and RF device microcavities, controlling thermal deformation. In mold manufacturing, it increases cooling efficiency by 30% in conformal cooling mold channels and micro-injection nozzles, enabling supportless printing. Finally, in emerging fields like space manufacturing (microgravity stress control) and metamaterial lattices (acoustic performance customization), it enables adaptive parameter systems and cross-scale applications.

[0049] 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.

[0050] 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 path planning method for LPBF metal additive manufacturing based on an active interlayer thermal stress release mechanism, characterized in that, include: S1. Set one or more stress relief regions within the outline of the slice layer of the 3D model, and use them as the target slice layer; wherein, the stress relief region is a weak scan region or a non-scan region; S2. Obtain multiple partitions of the target slice layer contour range by which the stress relief region is divided, and plan the scanning path for each partition. S3. Control the laser to scan each partition according to its set scanning path, and after completing the scanning of a target partition, take the adjacent partitions of the target partition as new target partitions for scanning, until the scanning of all partitions of the target slice layer is completed. S4. Switch to the next slice layer of the 3D model and use it as the new target slice layer. Set a stress release area in the new target slice layer that is similar to the original target slice layer, and the new stress release area and the original stress release area adopt an interlayer misalignment design. S5. Repeat steps S2 to S4 until all slice layers in the entire 3D model have been scanned.

2. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, In the scanning of the stress relief area, the laser energy density used is 0-40% of the ordinary laser energy density, where the ordinary laser energy density is the laser energy density used to scan multiple zones; When the laser energy density is 0% of the ordinary laser energy density, the stress release area is a non-scanning area; when the laser energy density is any of the remaining values, the stress release area is a weakly scanned area.

3. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, The stress relief zone is 5-15% of the total area of ​​the target slice layer.

4. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, The stress relief area is configured as a joint type, a cavity type, or a polygonal boundary type. The seam type is to set a continuous seam strip of a set width at each partition boundary, that is, to divide the outline range of the target slice layer into multiple partitions by a continuous line segment of a set width; The cavity type is obtained by setting a circular or polygonal non-scanning area as a cavity inside each partition after obtaining multiple partitions. The polygonal boundary method is to divide the outline of the target slice layer into an arbitrary number of polygons, and the edges of the polygons serve as the stress relief areas.

5. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, In the target slice layer, each partition forms an independent region.

6. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, The stress relief region in the target slice layer is taken as the target stress relief region, and the stress relief region in the slice layer adjacent to the target slice layer is taken as the adjacent stress relief region. The target stress relief region is rotated by a set angle with the center point of the target slice layer as a reference to obtain the adjacent stress relief region.

7. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 6, characterized in that, In the 3D model, the rotation angle of the stress relief area varies randomly between every two slice layers.

8. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, The stress relief region in the target slice layer is taken as the target stress relief region, and the stress relief region in the slice layer adjacent to the target slice layer is taken as the adjacent stress relief region. The target stress relief region is translated by a set distance to obtain the adjacent stress relief region.

9. The LPBF metal additive manufacturing path planning method based on the active interlayer thermal stress release mechanism according to claim 1, characterized in that, The scan path for each partition in the target slice layer is either random or linear.

10. An LPBF metal additive manufacturing path planning system based on an active interlayer thermal stress release mechanism, characterized in that, include: The setting module is used to set one or more stress relief regions within the outline of a slice layer of a 3D model, and to serve as the target slice layer; wherein, the stress relief region is a weakly scanned region or a non-scanned region; The acquisition module is used to acquire multiple partitions of the stress relief region in relation to the contour range of the target slice layer, and to plan a scanning path for each partition. The control module is used to control the laser to scan each partition according to its corresponding scanning path, and after completing the scanning of a target partition, to scan the adjacent partitions of the target partition as new target partitions, until the scanning of all partitions of the target slice layer is completed. The conversion module is used to convert to the next slice layer of the 3D model and use it as the new target slice layer. The new target slice layer sets a stress relief area similar to the original target slice layer, and the new stress relief area and the original stress relief area adopt an interlayer misalignment design. The loop module is used to repeat steps S2 to S4 until all slice layers in the entire 3D model have been scanned.

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