Electric arc additive manufacturing method of double-curvature part

Abstract

The invention belongs to the technical field of arc fuse deposition forming, and particularly relates to an arc additive manufacturing method of a double-curvature part, the stress distribution and deformation condition of a single part in the arc additive forming process are obtained through analog simulation, and a multi-part model coupling scheme is designed according to the model structure characteristics of the part. And matching design is carried out aiming at a high-stress area in the stress distribution and a high-deformation area in the deformation condition, and meanwhile, a plurality of connecting transition areas and reinforcing ribs are added so that the local cross section of the part can be converted into a more stable polygonal structure. According to the method, the high-stress / high-deformation area of the single part is positioned through analog simulation, multi-part model coupling design and transition area connection are combined, reinforcing rib optimization is performed, additional tools are not needed in the additive manufacturing and heat treatment process through iterative optimization, and the problems that the tool input cost is low and the tool adaptability is poor are thoroughly avoided.

Description

Technical Field

[0001] This invention belongs to the field of arc wire deposition forming technology, specifically, it relates to an arc additive manufacturing method for hyperbolic parts, applicable to the arc wire additive manufacturing of large-size aluminum alloy hyperbolic variable cross-section components. Background Technology

[0002] Arc additive manufacturing technology uses metal wire as raw material and an electric arc as a heat source. It relies on machine tools, robotic arms, or other actuators to manufacture dense metal components through a layer-by-layer welding process. Compared to traditional manufacturing processes, it eliminates the need for molds, shortens the overall manufacturing cycle, offers high flexibility, and allows for rapid response to designs, thus possessing broad application prospects in aerospace, automotive, and shipbuilding industries.

[0003] However, in arc additive manufacturing, the cyclic heating characteristic of the electric arc heat source generates a complex temperature field, resulting in high residual stress and macroscopic deformation in the components. As the forming size increases, the residual stress and deformation typically increase as well, not only reducing the performance and appearance of the structural components but also causing unpredictable deformation during subsequent heat treatment and machining processes, potentially leading to product cracking and scrapping. Therefore, deformation control in arc additive manufacturing products generally employs methods such as path planning and process parameter optimization, stiffener design, allowance addition, tooling design, dimensional compensation, and thermal straightening. However, for double-curvature, high aspect ratio, and variable cross-section structures, there is still no effective manufacturing method to suppress deformation and adjust stress distribution.

[0004] Patent application number 202411150375.3 discloses a high-precision additive manufacturing method for open-type thin-walled compartments. This method transforms the open structure into a more stable closed structure and, through a sandwich design, converts the weakly rigid thin-walled structure into a more rigid sandwich structure, reducing the risk of cracking and deformation during additive manufacturing and heat treatment. However, this method is not suitable for fabricating high aspect ratio, double-curvature variable cross-section structures using arc additive manufacturing processes, nor does it optimize the stress magnitude and distribution during the forming process.

[0005] Patent application number 202411656789.6 discloses a method for manufacturing a split-type irregular thin-walled cover plate. The method involves assembling symmetrical cover plates and then performing integral additive manufacturing, finally separating the left and right cover plates by wire cutting. This method is only suitable for symmetrical structures and is not applicable to additive manufacturing of structures with high aspect ratios and variable cross-sections, nor does it optimize or adjust the stress magnitude, stress distribution, and deformation during the forming process.

[0006] Patent application number 202210755323.6 discloses an arc additive manufacturing method for a thin-walled aluminum alloy shell with longitudinal internal stiffeners. The method employs a strategy of slicing the longitudinal internal stiffeners along the component axis and stacking them together in one step. Simultaneously, by extracting the main shape contour paths of the inner shell and each longitudinal internal stiffener, and then planning the filling paths within the contours, multiple independent paths are connected end to end in an orderly manner, realizing the one-step circumferential stacking of the stacked layers. This reduces the number of arc breaks and effectively avoids problems such as arc gun interference caused by the forming sequence, significantly improving the forming quality and efficiency of the component. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an electric arc additive manufacturing method for hyperbolic parts, which enables the additive fabrication of aluminum alloy hyperbolic variable cross-section structural parts without the need for tooling design and investment, and with low deformation risk.

[0008] According to the present invention, an arc additive manufacturing method for a hyperbolic part is provided. The stress distribution and deformation of a single part during the arc additive forming process are obtained through simulation. A multi-part model coupling scheme is designed based on the structural characteristics of the part model. Matching design is performed on the high-stress area in the stress distribution and the high-deformation area in the deformation. At the same time, multiple connection transition areas and reinforcing ribs are added to transform the local cross-section of the part into a more stable polygonal structure. After optimizing and iterating the model coupling scheme and the connection transition area design, the forming stress control and stress distribution optimization are completed and the local deformation is eliminated. Thus, the part does not need to use external machining to suppress deformation during the arc additive manufacturing and subsequent heat treatment process.

[0009] Furthermore, the specific steps of the electric arc additive manufacturing method for the hypercurvature part are as follows: Step S1: Establish an arc additive manufacturing simulation model for a single part using simulation methods, set material parameters, heat source parameters and boundary conditions that match the actual forming process, and obtain stress distribution data and deformation data of a single part during forming after running the simulation. Step S2: Based on the model structural features, stress distribution data and deformation data obtained in step S1, introduce multiple part models that are the same as or similar to the single part, and construct an initial scheme for multi-part model coupling by adjusting the placement of the models. Step S3: For the high stress area and high deformation area located in step S1, and in conjunction with the initial coupling scheme in step S2, design the position, size and shape of the connecting transition area, and at the same time design the arrangement and cross-sectional size of the reinforcing ribs to ensure that the local cross-section is transformed into a polygonal structure through the connecting transition area. Step S4: Verify the magnitude of forming stress, stress distribution, and deformation of the coupled model designed in Step S3. If the preset design requirements are met, proceed to the next step. If not, return to Step S2 to adjust the coupling scheme or Step S3 to optimize the transition zone and stiffener design. Repeat Steps S2-S4 until the verification is passed. Step S5: Output the verified multi-part integrated additive manufacturing model for subsequent arc additive forming operations.

[0010] Furthermore, in the multi-part model coupling design, the multiple part models introduced are part models with the same structure or part models with similar structures and matching curvature and wall thickness characteristics. By adjusting the placement angle of the models on the substrate and the spacing between adjacent models, the high-stress areas and low-stress areas of different models can compensate for each other and the high deformation directions can cancel each other out. Then, through the subsequent connection transition area design, the multiple dispersed part models are integrated into an integrated coupling model.

[0011] Furthermore, the design of the connection transition zone and reinforcing ribs is based on the characteristics of the model structure, the magnitude and distribution of forming stress, and the deformation trend. Priority is given to matching the design for high stress areas and high deformation areas such as places where the wall thickness changes abruptly, places where the curvature changes drastically, and cantilever sections with a length-to-diameter ratio greater than a preset threshold.

[0012] Furthermore, the peak forming stress in each region of the coupling model does not exceed 10% of the yield strength of the aluminum alloy material used in the part in the deposition state, there is no stress concentration in the thin wall area of ​​the part to avoid cracking, and the maximum deformation of the coupling model is <1mm / 1000mm.

[0013] Furthermore, the heat source parameters in step S1 correspond to a double ellipsoidal heat source model, the material parameters include the thermal conductivity, specific heat capacity and deposited yield strength of the aluminum alloy, and the boundary conditions include ambient temperature and heat dissipation coefficient.

[0014] Furthermore, the connection transition zone transforms the local cross-section of the part into a polygonal structure, thereby offsetting residual stress in the local area through the geometric stability of the polygon.

[0015] Furthermore, the size of the substrate needs to cover the overall projection range of the multi-part coupling model, and the substrate thickness needs to ensure the stability of the support.

[0016] Furthermore, the integrated additive manufacturing model exported in step S5 is in a special format for additive manufacturing, which is used to import the electric arc additive manufacturing equipment for path planning.

[0017] Furthermore, the path planning parameters of the electric arc additive manufacturing equipment are adapted to the integrated model.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses simulation to locate the high stress / high deformation zone of a single part, and combines multi-part model coupling design and connection transition zone and stiffener optimization. After iterative optimization, the peak forming stress can be kept below 10% of the material's deposited yield strength, the maximum deformation is <1mm / 1000mm, and there is no stress concentration in the thin wall area. This allows additive manufacturing and heat treatment processes to be carried out without external processing equipment, completely avoiding the problems of tooling investment costs and poor tooling adaptability.

[0019] 2. This invention, through multi-model coupling and local structural stabilization design, is specifically adapted to the stress distribution characteristics of hyperbolic structures and the heat source characteristics of arc additive manufacturing, filling the technical gap in arc additive manufacturing of such parts.

[0020] 3. This invention forms an integrated manufacturing model by coupling multiple part models, which can realize the simultaneous deposition and forming of multiple double-curvature weak stiffness parts, greatly reducing the auxiliary time such as clamping and positioning; at the same time, through precise stress-deformation control, the extra material allowance required for deformation compensation is reduced, significantly improving the material utilization rate, and finally realizing low-cost and high-efficiency integrated arc additive manufacturing of such parts. Attached Figure Description

[0021] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the hypercurvature weak stiffness variable cross section structure of the present invention; Figure 2 This is a schematic diagram of the integrated model after coupling optimization according to the present invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0023] Example 1: This embodiment provides an arc additive manufacturing method for hyperbolic parts, including the following specific steps: Step S1, Single-part stress-deformation simulation: Through simulation, three hyperbolic components of different sizes were obtained. The component material was selected as 2219 aluminum alloy. Based on the adopted double ellipsoidal heat source model and after setting relevant thermal boundary conditions, the additive forming process of a single part was simulated, and stress distribution cloud map and deformation data were output to locate high stress area and high deformation area.

[0024] Step S2, Multi-model Coupled Design: Three of the above-mentioned part models are introduced, and the placement angle and spacing of the three part models are adjusted. A substrate of appropriate size is selected, and a connection transition zone is added every 150-250mm in the deposition height direction, and local reinforcing ribs are added.

[0025] Step 3: Design of the transition zone and reinforcing ribs: The design of the connection transition zone and the stiffener design are optimized to transform the local cross-section into a polygonal structure with formability.

[0026] Step S4, Stress-deformation check: The integrated model after simulation coupling was used to verify its forming stress magnitude, stress distribution and deformation. The peak stress was 9MPa, which is 9.5% of the deposited yield strength of 2219 aluminum alloy, and there was no stress concentration in the thin wall area. The maximum deformation was 0.8mm / 1000mm. The peak stress and maximum deformation were both located in the connection transition zone, which met the design requirements.

[0027] Step S5, Integrated Model Output: The integrated model that meets the standards is exported into an additive manufacturing format, and the integrated deposition molding of three parts is completed. The molding accuracy is consistent with the simulation results, and there are no cracks or deformation defects.

[0028] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0029] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An electric arc additive manufacturing method for a hypercurvature part, characterized in that, By simulating the stress distribution and deformation of a single part during the arc additive manufacturing process, a multi-part model coupling scheme is designed based on the structural characteristics of the part model. Matching designs are performed for high-stress areas in the stress distribution and high-deformation areas in the deformation. At the same time, multiple connection transition zones and reinforcing ribs are added to transform the local cross-section of the part into a more stable polygonal structure. After optimizing and iterating the model coupling scheme and connection transition zone design, the forming stress control and stress distribution optimization are completed and local deformation is eliminated. Thus, the part does not need to use external machining equipment to suppress deformation during arc additive manufacturing and subsequent heat treatment.

2. The method for arc additive manufacturing of hypercurvature parts according to claim 1, characterized in that, The specific steps are as follows: Step S1: Establish an arc additive manufacturing simulation model for a single part using simulation methods, set material parameters, heat source parameters and boundary conditions that match the actual forming process, and obtain stress distribution data and deformation data of a single part during forming after running the simulation. Step S2: Based on the model structural features, stress distribution data and deformation data obtained in step S1, introduce multiple part models that are the same as or similar to the single part, and construct an initial scheme for multi-part model coupling by adjusting the placement of the models. Step S3: For the high stress area and high deformation area located in step S1, and in conjunction with the initial coupling scheme in step S2, design the position, size and shape of the connecting transition area, and at the same time design the arrangement and cross-sectional size of the reinforcing ribs to ensure that the local cross-section is transformed into a polygonal structure through the connecting transition area. Step S4: Verify the magnitude of forming stress, stress distribution, and deformation of the coupled model designed in Step S3. If the preset design requirements are met, proceed to the next step. If not, return to Step S2 to adjust the coupling scheme or Step S3 to optimize the transition zone and stiffener design. Repeat Steps S2-S4 until the verification is passed. Step S5: Output the verified multi-part integrated additive manufacturing model for subsequent arc additive forming operations.

3. The method for arc additive manufacturing of hypercurvature parts according to claim 2, characterized in that, In the multi-part model coupling design, the multiple part models introduced are part models with the same structure or part models with similar structures and matching curvature and wall thickness characteristics. By adjusting the placement angle of the models on the substrate and the distance between adjacent models, the high stress area and low stress area of ​​different models can compensate for each other and the high deformation direction can cancel each other out. Then, through the subsequent connection transition area design, the multiple dispersed part models are integrated into an integrated coupling model.

4. The method for arc additive manufacturing of hypercurvature parts according to claim 2, characterized in that, The design of the connection transition zone and reinforcing ribs is based on the characteristics of the model structure, the magnitude and distribution of forming stress, and the deformation trend. Priority is given to matching the design of high stress and high deformation areas such as areas with abrupt changes in wall thickness, areas with drastic changes in curvature, and cantilever sections with a length-to-diameter ratio greater than a preset threshold.

5. The method for arc additive manufacturing of hypercurvature parts according to claim 2, characterized in that, The peak forming stress in each region of the coupling model does not exceed 10% of the yield strength of the aluminum alloy material used in the part in the deposition state. There is no stress concentration in the thin wall area of ​​the part to avoid cracking. The maximum deformation of the coupling model is <1mm / 1000mm.

6. The method for arc additive manufacturing of hypercurvature parts according to claim 2, characterized in that, The heat source parameters in step S1 correspond to a double ellipsoidal heat source model. The material parameters include the thermal conductivity, specific heat capacity, and deposited yield strength of the aluminum alloy. The boundary conditions include ambient temperature and heat dissipation coefficient.

7. The method for arc additive manufacturing of hypercurvature parts according to claim 2, characterized in that, The connection transition zone is a polygonal structure that transforms the local cross-section of the part in order to offset the residual stress in the local area through the geometric stability of the polygon.

8. The method for arc additive manufacturing of hypercurvature parts according to claim 3, characterized in that, The size of the substrate needs to cover the overall projection range of the multi-part coupled model, and the thickness of the substrate can ensure the stability of the support.

9. The method for arc additive manufacturing of hypercurvature parts according to claim 2, characterized in that, The integrated additive manufacturing model exported in step S5 is in a special format for additive manufacturing, which is used to import the electric arc additive manufacturing equipment for path planning.

10. The method for arc additive manufacturing of hypercurvature parts according to claim 9, characterized in that, The path planning parameters of the electric arc additive manufacturing equipment are adapted to the integrated model.

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