A method for controllable buckling deformation of thin-walled structures by powder bed fusion
By altering heat accumulation and temperature gradient during laser powder bed melting, and employing layer-by-layer remelting, staged remelting, and heat preservation treatment, the uncontrollable buckling deformation problem of thin-walled structures was solved, enabling active control of buckling deformation modes and improving forming accuracy and structural stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING UNIV OF SCI & TECH
- Filing Date
- 2026-04-21
- Publication Date
- 2026-06-16
AI Technical Summary
Existing technologies make it difficult to actively and controllably adjust the buckling deformation mode and deformation amount of thin-walled structures during laser powder bed melting. In particular, there is a lack of systematic technical solutions for buckling direction reversal, buckling enhancement, and unidirectional deformation control, which makes it difficult to guarantee forming accuracy and structural stability.
By altering the heat accumulation and temperature gradient of thin-walled structures, and employing methods such as layer-by-layer remelting, staged remelting, and heat preservation treatment, controllable buckling deformation of thin-walled structures can be achieved. This includes reversing the buckling direction through layer-by-layer remelting, increasing the deformation amount through staged remelting, and reducing the deformation amount through heat preservation treatment.
Active control of buckling deformation mode of thin-walled structure was achieved, which improved forming accuracy and structural stability, and expanded the application range of thin-walled structure in complex curved surface and functional structure design.
Smart Images
Figure CN122210076A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of laser additive manufacturing and rapid prototyping technology, specifically relating to a method for controllable buckling deformation of powder bed molten thin-walled structures. Background Technology
[0002] Laser powder bed melting (LBD), a typical metal additive manufacturing technology, boasts advantages such as high forming accuracy, high material utilization, and great freedom in structural design, and has been widely applied in aerospace, biomedical, and precision manufacturing fields. Especially driven by the demands for lightweighting and high performance, thin-walled structures, due to their excellent specific strength and specific stiffness characteristics, have become an important research and application focus in LBD technology.
[0003] However, due to the significant localized rapid heating and cooling cycles during laser powder bed melting, when the geometry, aspect ratio, or forming height of a thin-walled structure is large, the thermal stress often exceeds the structural stability critical condition, leading to local buckling or even overall buckling deformation. Because of the transient and spatially non-uniform nature of heat input, the buckling of thin-walled structures not only manifests as unstable deformation, but more importantly, the buckling mode exhibits significant randomness and unpredictability, potentially presenting as symmetrical buckling, parallel buckling, or overall buckling. This type of buckling deformation not only reduces forming accuracy, affecting the dimensional consistency and service performance of the structure, but may also lead to forming failure, severely restricting the application of thin-walled structures in engineering.
[0004] To address the deformation problem of laser powder bed molten thin-walled structures, existing technologies mainly reduce residual stress or suppress deformation by optimizing forming process parameters, adjusting scanning strategies, and introducing preheating or post-processing. For example, reducing energy density, changing the scanning path, or using substrate preheating can mitigate the temperature gradient; or deformation can be eliminated after forming through heat treatment or mechanical straightening. However, most of these methods aim at deformation suppression or passive correction, making it difficult to precisely control the buckling deformation mode and amount during the forming process.
[0005] Currently, there is a lack of a method to actively guide and controllably adjust the buckling deformation of thin-walled structures based on their original buckling behavior during laser powder bed melting manufacturing. In particular, there is a lack of systematic technical solutions for buckling direction reversal, buckling enhancement, and unidirectional deformation control.
[0006] Therefore, there is an urgent need to propose a method for controlling the buckling deformation of powder bed fusion thin-walled structures, which can make full use of the thermal stress effect during the laser powder bed fusion process, and achieve active and controllable adjustment of the buckling deformation mode and deformation amount of thin-walled structures without significantly increasing the manufacturing complexity, thereby expanding the application scope of additive manufacturing thin-walled structures in complex curved surface and functional structure design. Summary of the Invention
[0007] To address the shortcomings and deficiencies of existing technologies, this invention proposes a method for controllable buckling deformation of powder bed molten thin-walled structures, enabling active control of the buckling deformation mode and deformation amount of thin-walled structures.
[0008] The technical solution adopted in this invention is:
[0009] A method for controllable buckling deformation of powder bed molten thin-walled structures is proposed. In the process of manufacturing laser powder bed molten thin-walled structures, controllable buckling deformation of the wall structure is achieved by changing the heat accumulation and temperature gradient of the thin-walled structure.
[0010] Furthermore, by selecting the target wall surface of the thin-walled structure and remelting it layer by layer, the direction of the buckling deformation of the thin-walled structure is reversed, that is, the axial direction of the buckling deformation is opposite to that of the thin-walled structure manufactured without the layer-by-layer remelting method.
[0011] Furthermore, the layer-by-layer remelting process involves setting up a remelting region within a local thickness range outside the target wall surface and using an interlayer rotation scanning strategy for remelting.
[0012] Furthermore, the target wall surface of the thin-walled structure is selected for staged remelting to increase the concave-convex deformation of the original buckling deformation of the thin-walled structure. That is, compared with the thin-walled structure manufactured without staged remelting, the axial concave-convex direction of buckling deformation remains unchanged, but the deformation amount increases.
[0013] Furthermore, the staged remelting process is to perform remelting after a selected height, where the selected height is the critical buckling height h. The calculation formula for the critical buckling height h is shown in formula (1). At the same time, a staged remelting area is set within the local thickness range outside the target wall, and a scanning strategy of interlayer rotation is used for remelting.
[0014] (1)
[0015] Where h is the critical buckling height. Let K be the energy density of each layer, and K be the local buckling coefficient of the thin wall, which is determined by the boundary conditions of the thin wall. It is the equivalent thermal expansion coefficient. t is Poisson's ratio, b is the side length of the thin-walled structure, and t is the wall thickness of the thin-walled structure.
[0016] Furthermore, the local thickness of the outer side of the target wall in both the layer-by-layer remelting process and the staged remelting process is half the thickness of the outer side of the target wall.
[0017] Furthermore, both the layer-by-layer remelting process and the staged remelting process are carried out at a predetermined energy density, which is greater than or equal to the original design energy density.
[0018] Furthermore, the predetermined energy density is 1 to 1.5 times the original design energy density.
[0019] Furthermore, by adding an insulation structure around the target wall, the insulation structure is manufactured simultaneously with a high energy density greater than the original design energy density. The target wall is insulated through the heat conduction of the powder medium, reducing the temperature gradient of the target wall and decreasing the thermal stress, thereby reducing the amount of buckling deformation of the thin-walled target wall.
[0020] Furthermore, the thin-walled structure is a regular polygonal structure, and the target wall surface is any one or more walls of the thin-walled structure.
[0021] The beneficial effects of this invention are as follows: During the manufacturing process, this invention guides the structure to generate a desired and controllable buckling deformation mode through a driving force primarily based on thermal stress, thereby forming specific geometric deformation characteristics. This achieves active control over the buckling behavior of thin-walled structures and can be used for customized manufacturing of three-dimensional curved structures and applicability verification of online monitoring systems. Without controlling the concave-convex direction of buckling deformation, the structure may exhibit a bending trend opposite to the design target in different batches or regions, leading to difficulties in ensuring geometric accuracy, misalignment of assembly interfaces, further stress concentration, and even inducing crack propagation. Simultaneously, uncontrolled buckling modes are often near critical instability, prone to concave-convex reversal or abrupt deformation, affecting structural stability and the reliability of online monitoring judgments. The significance of controllable buckling deformation lies in achieving the designability and repeatability of buckling modes, while reducing the amount of deformation improves forming accuracy and service reliability. Together, they realize the transformation of thin-walled structures from passive instability to active control, providing a mechanical basis for the customized manufacturing of three-dimensional curved structures and the stability verification of online monitoring systems.
[0022] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description
[0023] Figure 1 Initial buckling deformation diagrams of thin-walled structures with different heights;
[0024] Figure 2 This is a schematic diagram of the region division in the layer-by-layer remelting process in Example 1;
[0025] Figure 3 This is a diagram showing the buckling deformation characteristics of the target wall surface after layer-by-layer remelting in Example 1;
[0026] Figure 4 This is a schematic diagram of the region division in the staged remelting process of Example 2;
[0027] Figure 5 This is a diagram showing the buckling deformation characteristics of the target wall surface after the staged remelting treatment in Example 2;
[0028] Figure 6 This is a schematic diagram of the solid insulation treatment in Example 3;
[0029] Figure 7 This is a diagram showing the buckling deformation characteristics of the target wall surface after the solid insulation treatment in Example 3;
[0030] Figure 8 This is a diagram illustrating the controllable buckling deformation effect of the thin-walled structure of the present invention.
[0031] Figure 9 This is a flowchart of the method for controllable buckling deformation of powder bed molten thin-walled structures according to the present invention. Detailed Implementation
[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0033] A method for controllable buckling deformation of powder bed molten thin-walled structures is disclosed. In the manufacturing process of laser powder bed molten Ti-6Al-4V thin-walled structures, controllable buckling deformation of the wall structure is achieved by altering the heat accumulation and temperature gradient of the thin-walled structure. Combined with... Figure 9 The method for controllable buckling deformation of powder bed molten thin-walled structure of the present invention can be implemented in three ways, which are described in the following three embodiments. Specific Implementation Example 1
[0035] A 3D model of a thin-walled structure with a cross-sectional dimension of 30 mm × 30 mm, heights of 30 mm, 40 mm, and 50 mm, and a wall thickness of 0.5 mm was established. The 3D model was sliced and assigned forming process parameters. The slice thickness was 0.03 mm, the original laser power was 200 W, and the original scanning speed was 1000 mm / s. The thin-walled structure was manufactured using a Concept Laser M2 laser powder bed melting system. The geometric contour of the thin-walled structure was detected using a FreeScan Cambo 3D scanner to acquire point cloud data. The point cloud data was imported into the Geomagic Control X software, and the original buckling deformation mode and deformation amount of the thin-walled structure were obtained through model alignment and 3D comparison. (See also...) Figure 1 , Figure 1 The figure shows the initial buckling deformation of thin-walled structures with different heights. In the initial buckling, the target wall surface exhibits an axial deformation distribution of first convex and then concave.
[0036] In the process of manufacturing thin-walled structures using laser powder bed fusion, the target wall surface of the thin-walled structure is selected for layer-by-layer remelting, thereby reversing the direction of the buckling deformation of the thin-walled structure:
[0037] A three-dimensional model of a thin-walled structure with a cross-sectional dimension of 30 mm × 30 mm, heights of 30 mm, 40 mm, and 50 mm, and a wall thickness of 0.5 mm was established. The 3D model was sliced and given forming process parameters. The slice thickness was 0.03 mm, the original laser power was 200 W, and the original scanning speed was 1000 mm / s. Using a predetermined high laser power of 250 W and a scanning speed of 1000 mm / s, the target wall surface was remelted layer by layer. A remelting region was set within the outer 1 / 2 thickness range of the target wall surface, i.e., the target wall thickness was 0.5 mm, and the remelting region was selected within the outer 0.25 mm thickness range of the target wall surface. The thin-walled structure was manufactured using a Concept Laser M2 laser powder bed melting system, employing a scanning strategy of 90° interlayer rotation. Figure 2 The diagram shown illustrates the region division during the layer-by-layer remelting process.
[0038] By progressively increasing the heat input to the remelted regions, the heat accumulation and internal stress on the wall surface are increased, thus reversing the buckling deformation mode. The buckling deformation characteristics of the target wall surface after progressive remelting are detected using a 3D scanner. Figure 3 The image shows the buckling deformation characteristics of the target wall after layer-by-layer remelting. As the deposition height increases, the target wall undergoes a concave-convex reversal, meaning the target wall is first concave and then convex. Specific Implementation Example 2
[0040] A 3D model of a thin-walled structure with a cross-sectional dimension of 30 mm × 30 mm, heights of 30 mm, 40 mm, and 50 mm, and a wall thickness of 0.5 mm was established. The 3D model was sliced and assigned forming process parameters. The slice thickness was 0.03 mm, the original laser power was 200 W, and the original scanning speed was 1000 mm / s. The thin-walled structure was manufactured using a Concept Laser M2 laser powder bed melting system. The geometric contour of the thin-walled structure was detected using a FreeScan Cambo 3D scanner to acquire point cloud data. The point cloud data was imported into the Geomagic Control X software, and the original buckling deformation mode and deformation amount of the thin-walled structure were obtained through model alignment and 3D comparison. (See also...) Figure 1 , Figure 1 The figure shows the initial buckling deformation of thin-walled structures with different heights. In the initial buckling, the target wall surface exhibits an axial deformation distribution of first convex and then concave.
[0041] By selecting the target wall surface of the thin-walled structure for staged remelting, the original buckling deformation of the thin-walled structure is increased, meaning that compared to a thin-walled structure manufactured without layer-by-layer remelting, where the axial concave-convex direction of buckling deformation remains unchanged, the deformation amount is increased.
[0042] A three-dimensional model of a thin-walled structure with a cross-sectional dimension of 30 mm × 30 mm, heights of 30 mm, 40 mm, and 50 mm, and a wall thickness of 0.5 mm was established. The 3D model was sliced and given forming process parameters. The slice thickness was 0.03 mm, the original laser power was 200 W, and the original scanning speed was 1000 mm / s. Based on the critical height calculation formula:
[0043] (1)
[0044] Where h is the critical buckling height. Let K be the energy density of each layer, and K be the local buckling coefficient of the thin wall, which is determined by the boundary conditions of the thin wall. For example, in a simply supported quadrilateral thin-walled structure under uniaxial compression, K=4. Here, for a quadrilateral thin-walled structure, K=4. It is the equivalent thermal expansion coefficient. Let b be Poisson's ratio, b be the side length of the thin-walled structure, and t be the wall thickness of the thin-walled structure. In this embodiment, the critical height of the laser powder bed melting thin-walled structure is calculated to be 30 mm using formula (1). A predetermined combination of high laser power (250 W) and scanning speed (1000 mm / s) is used to perform staged remelting on the target wall surface above 30 mm in height. A remelting area is set within 1 / 2 of the thickness of the outer side of the target wall surface, i.e., the target wall surface thickness is 0.5 mm, and the remelting area is selected within 0.25 mm of the outer side of the target wall surface. A scanning strategy with interlayer rotation of 90° is used for remelting. The thin-walled structure is manufactured using the Concept Laser M2 laser powder bed melting equipment. Figure 4 The diagram shown illustrates the zone division during the staged remelting process.
[0045] The staged remelting process involves remelting after a selected height (i.e., after the critical buckling height h, the calculation formula for the critical buckling height h is shown in formula (1)). At the same time, a remelting area is set within a local thickness range outside the target wall (for example, the target wall thickness is 0.5 mm, and the remelting area is selected as the 0.25 mm thickness range outside the target wall), and a scanning strategy of interlayer rotation is used for remelting.
[0046] The buckling deformation characteristics of the target wall after stage remelting were detected using a 3D scanner. Figure 5The figure shows the buckling deformation characteristics of the target wall surface after staged remelting. Compared with the thin-walled structure manufactured without staged remelting, the axial concave-convex direction of the buckling deformation remains unchanged, but the buckling deformation increases to 1.56 mm. Specific Implementation Example 3
[0048] A 3D model of a thin-walled structure with a cross-sectional dimension of 30 mm × 30 mm, heights of 30 mm, 40 mm, and 50 mm, and a wall thickness of 0.5 mm was established. The 3D model was sliced and assigned forming process parameters. The slice thickness was 0.03 mm, the original laser power was 200 W, and the original scanning speed was 1000 mm / s. The thin-walled structure was manufactured using a Concept Laser M2 laser powder bed melting system. The geometric contour of the thin-walled structure was detected using a FreeScan Cambo 3D scanner to acquire point cloud data. The point cloud data was imported into the Geomagic Control X software, and the original buckling deformation mode and deformation amount of the thin-walled structure were obtained through model alignment and 3D comparison. (See also...) Figure 1 , Figure 1 The figure shows the initial buckling deformation of thin-walled structures with different heights. In the initial buckling, the target wall surface exhibits an axial deformation distribution of first convex and then concave.
[0049] Solid thermal insulation treatment is applied to the target wall surface of the thin-walled structure to reduce the amount of deformation during the initial buckling deformation and delay the buckling period. In other words, compared to a thin-walled structure manufactured without thermal insulation treatment, the axial concave-convex direction of buckling deformation remains unchanged, but the amount of deformation is reduced.
[0050] A three-dimensional model of a thin-walled structure with a cross-sectional dimension of 30 mm × 30 mm, heights of 30 mm, 40 mm, and 50 mm, and a wall thickness of 0.5 mm was established. The 3D model was sliced and given forming process parameters. The slice thickness was 0.03 mm, the original laser power was 200 W, and the original scanning speed was 1000 mm / s. Insulation blocks with a cross-sectional dimension of 25 mm × 5 mm and heights of 30 mm, 40 mm, and 50 mm were added to the inner side of the target wall. These insulation blocks were manufactured using a predetermined combination of high laser power (250 W) and a predetermined scanning speed (1000 mm / s). The target wall was insulated through heat conduction via the powder medium, adjusting the temperature gradient of the target wall to reduce buckling deformation of the thin-walled structure. Figure 6 The diagram shown is a schematic of solid insulation treatment.
[0051] The buckling deformation characteristics of the target wall after stage remelting were detected using a 3D scanner. Figure 7The figure shows the buckling deformation characteristics of the target wall after thermal insulation treatment. The thermal insulation treatment reduces the heat accumulation and temperature gradient of the target wall, resulting in a reduction of the buckling deformation of the target wall to 0.65 mm.
[0052] Any one or more of the layer-by-layer remelting process, staged remelting process, and heat preservation process can be implemented individually or in combination as needed. Figure 8 The controllable buckling deformation effect of the thin-walled structure of the present invention is presented.
[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for controllable buckling deformation of a powder bed molten thin-walled structure, characterized in that, In the process of manufacturing thin-walled structures using laser powder bed melting, controllable buckling deformation of the wall structure is achieved by changing the heat accumulation and temperature gradient of the thin-walled structure.
2. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to claim 1, characterized in that, By selecting the target wall surface of the thin-walled structure and remelting it layer by layer, the direction of the buckling deformation of the thin-walled structure is reversed, that is, the axial direction of the buckling deformation is opposite to that of the thin-walled structure manufactured without the layer-by-layer remelting method.
3. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to claim 2, characterized in that, Layer-by-layer remelting involves setting up remelting zones within a local thickness range outside the target wall and employing an interlayer rotation scanning strategy for remelting.
4. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to claim 1, characterized in that, By selecting the target wall surface of the thin-walled structure for staged remelting, the concave-convex deformation of the original buckling deformation of the thin-walled structure is increased. That is, compared with the thin-walled structure manufactured without staged remelting, the axial concave-convex direction of buckling deformation remains unchanged, but the amount of deformation is increased.
5. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to claim 4, characterized in that, The staged remelting process is to perform remelting after a selected height, where the selected height is the critical buckling height h. The calculation formula for the critical buckling height h is shown in formula (1). At the same time, a staged remelting area is set within the local thickness range outside the target wall, and a scanning strategy of interlayer rotation is used for remelting. （1） Where h is the critical buckling height. Let K be the energy density of each layer, and K be the local buckling coefficient of the thin wall, which is determined by the boundary conditions of the thin wall. It is the equivalent thermal expansion coefficient. t is Poisson's ratio, b is the side length of the thin-walled structure, and t is the wall thickness of the thin-walled structure.
6. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to any one of claims 2-5, characterized in that, The local thickness of the outer side of the target wall in both the layer-by-layer remelting process and the staged remelting process is half the thickness of the outer side of the target wall.
7. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to any one of claims 2-5, characterized in that, Both the layer-by-layer remelting process and the staged remelting process are carried out at a predetermined energy density, which is greater than or equal to the original design energy density.
8. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to claim 7, characterized in that, The predetermined energy density is 1 to 1.5 times the original design energy density.
9. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to claim 1, characterized in that, By adding an insulation structure around the target wall, the insulation structure is manufactured synchronously with a high energy density greater than the original design energy density. The target wall is insulated through the heat conduction of the powder medium, reducing the temperature gradient of the target wall and decreasing the thermal stress, thereby reducing the amount of buckling deformation of the thin-walled target wall.
10. The method for controllable buckling deformation of a powder bed molten thin-walled structure according to any one of claims 2-5 and 8-9, characterized in that, The thin-walled structure is a regular polygonal structure, and the target wall surface is any one or more walls of the thin-walled structure.