An arc additive-multiple loading integrated forming method of a large magnesium alloy aerospace structure

Abstract

This invention discloses an integrated arc additive manufacturing and multi-directional loading forming method for large magnesium alloy aerospace structural components, belonging to the field of magnesium alloy additive manufacturing technology. This invention, through component structural analysis and process planning, divides critical and non-critical areas, formulates a zoned loading strategy and deformation allocation scheme; it employs coordinated arc additive manufacturing and multi-directional loading, with critical areas using a "simultaneous additive manufacturing and loading" mode, real-time monitoring of temperature and deformation, and closed-loop control of loading parameters; variable cross-section areas utilize gradient slicing and spiral paths, while reinforcing rib areas employ dense paths, achieving integrated coordination of additive forming, stress control, and deformation optimization. This invention solves the defects of easy deformation, cracking, and poor interlayer bonding in the forming process of large magnesium alloy components, improving forming accuracy by more than 30%, tensile strength by 25%-40%, fatigue life by more than 50%, and reducing costs by 30%-50%, meeting the high requirements of the aerospace field and possessing significant engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology for large magnesium alloy components, and in particular relates to an integrated arc additive manufacturing-multi-directional loading forming method for large magnesium alloy aerospace structural components. It is especially suitable for the manufacturing of high-value aerospace typical components with complex structural features such as variable cross-sections and stiffeners, such as aircraft wing ribs and rocket supports. It realizes the integrated synergy of additive forming, stress control, and deformation optimization, thereby improving the forming quality and service reliability of the components. Background Technology

[0002] The aerospace industry has an increasingly urgent need for lightweight, high-strength, and high-precision large structural components. Magnesium alloys, as the lowest density metallic structural material, have advantages such as high specific strength, good damping properties, and strong recyclability, making them the preferred material for key components such as aircraft wing ribs and rocket supports. These components are mostly large and complex structures, generally exhibiting structural characteristics such as variable cross-section transitions, dense stiffeners, and alternating thin and thick walls. Moreover, they operate in harsh environments, requiring extremely high precision in forming, uniformity of microstructure, and mechanical properties.

[0003] Currently, the manufacturing of large magnesium alloy aerospace structural components mostly adopts traditional casting, forging and machining processes, which have drawbacks such as low material utilization, high mold dependence, long manufacturing cycle and high cost. In addition, it is difficult to adapt to the integrated forming of structures with variable cross sections and complex reinforcing ribs, and forming defects are prone to occur. Arc additive manufacturing technology, with its advantages of high material utilization, on-demand forming of complex structures, and no need for large molds, is gradually being applied to the manufacturing of magnesium alloy components. However, there are still many bottlenecks in the forming process of large aerospace components: First, during the forming process of large components, the layer-by-layer stacking of arc additives will generate uneven thermal stress. In addition, magnesium alloys have high thermal conductivity, large coefficient of thermal expansion, and poor plasticity, which can easily lead to defects such as component deformation, cracking, and poor interlayer bonding, seriously affecting the forming accuracy. Second, existing arc additive processes are mostly general-purpose and have not been designed for the structural characteristics of specific components such as aircraft wing ribs and rocket supports (such as stress concentration in variable cross-section areas and weak connection between stiffeners and the main body). This results in insufficient mechanical properties of key parts of the components, making it difficult to meet the high reliability requirements of the aerospace field. Third, in traditional processes, additive forming, stress control, and deformation correction are carried out in separate steps, which not only increases the manufacturing process and cycle, but may also introduce secondary stress due to subsequent processing, further deteriorating the performance of the components.

[0004] While some existing technologies attempt to combine loading processes with additive manufacturing, most involve unidirectional loading, which cannot adapt to the multi-directional stress characteristics of large aerospace components. Furthermore, they fail to achieve a deep integration of general processes with the manufacturing needs of specific high-value products, making it difficult to solve the forming challenges of specific components. Therefore, there is an urgent need for a forming method that integrates arc additive manufacturing and multi-directional loading for typical components such as aircraft wing ribs and rocket supports. This method would utilize precise control through zoned loading strategies and deformation distribution to address issues such as low forming accuracy, numerous defects, and uneven performance in large magnesium alloy aerospace structural components. Simultaneously, it would shorten manufacturing cycles, reduce costs, and promote the large-scale application of magnesium alloys in the aerospace field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an integrated arc additive manufacturing-multi-directional loading forming method for large magnesium alloy aerospace structural components. Specifically designed for the structural characteristics (variable cross-section, stiffeners, etc.) of typical components such as aircraft wing ribs and rocket supports, this invention designs a process scheme that achieves integrated synergy between arc additive manufacturing and multi-directional loading stress control and deformation optimization through precise control of zoned loading strategies and deformation distribution. This solves defects such as deformation, cracking, poor interlayer bonding, and insufficient performance of key components that occur during the forming process of large magnesium alloy components. It improves the forming accuracy, microstructure uniformity, and mechanical properties of components, while shortening the manufacturing cycle, increasing material utilization, and reducing manufacturing costs. This invention deeply integrates general additive manufacturing processes with the manufacturing needs of specific high-value aerospace products, strengthens application scenario protection, and promotes the highly reliable and large-scale application of magnesium alloys in the aerospace field.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An integrated arc additive manufacturing-multidirectional loading forming method for large magnesium alloy aerospace structural components is disclosed. This method is applicable to large magnesium alloy aerospace structural components with variable cross-sections and stiffener structures, such as aircraft wing ribs and rocket supports. The specific steps are as follows: 1) Component structure analysis and process planning: First, obtain the three-dimensional model of the target component, clarify the structural characteristics of the component, including the location, size, and transition slope of the variable cross-section area, the distribution, size, and connection method of the stiffeners with the main component, divide the critical stress area and non-critical stress area of ​​the component, and formulate an integrated process scheme of electric arc additive manufacturing and multi-directional loading based on the service stress requirements of the component. Determine the area division of the zoned loading, the loading direction, loading timing, loading force, and deformation distribution parameters of each area to ensure that the loading strategy is accurately matched with the structural characteristics and service requirements of the component. 2) Equipment Debugging and Tooling Preparation: Set up the integrated arc additive manufacturing-multi-directional loading equipment, including the arc additive manufacturing system (GTAW equipment, wire feeder), multi-directional loading system, temperature monitoring system, deformation monitoring system, and tooling fixtures; fix the magnesium alloy substrate to the worktable using the tooling fixtures to ensure accurate positioning and firm fixation of the substrate, and avoid displacement during the forming process; debug each piece of equipment to ensure that the arc additive manufacturing parameters, multi-directional loading parameters, temperature monitoring, and deformation monitoring all meet the preset requirements; 3) 3D modeling and path planning: 3D modeling software is used to optimize the 3D model of the target component, and structural optimization is performed on key loading areas to reduce stress concentration; the optimized 3D model is imported into slicing software for layered slicing, and the arc additive manufacturing path is planned based on the characteristics of the component partitions; at the same time, the additive manufacturing sequence and loading timing of each region are planned based on the partition loading strategy to achieve the coordinated operation of additive manufacturing and loading. 4) Material preparation and parameter setting: Select high-strength magnesium alloy wire suitable for aerospace requirements, grind and degrease the wire surface to remove the surface oxide layer and impurities; set the electric arc additive parameters, allocate parameters according to the area of ​​component loading and deformation, and set the multi-directional loading parameters for each area. 5) Integrated forming operation: Turn on the integrated arc additive manufacturing-multi-directional loading equipment, and carry out layer-by-layer additive manufacturing and multi-directional loading collaborative operation according to the planned additive manufacturing path and loading strategy; 6) Interlayer treatment: After each layer of additive manufacturing and loading is completed, surface oxides and waste residue are removed with a steel brush. Local grinding is performed at the joints of variable cross sections and the joints of reinforcing ribs to ensure the adhesion of the next layer of additive manufacturing. If local deformation exceeds the standard, it is corrected in real time through a multi-directional loading system before the next layer is formed. 7) Post-forming processing: After the overall additive manufacturing and loading of the component is completed, keep the tooling fixture in a fixed state and place the component in an air environment to cool slowly to room temperature to avoid secondary stress caused by rapid cooling; after cooling, remove the tooling fixture and use wire cutting to remove excess material to obtain the component of the target size. 8) Subsequent optimization treatment: The formed components are ground and polished to remove surface burrs and defects; Non-destructive testing (ultrasonic testing, radiographic testing) is carried out on key parts of the components (variable cross-section areas, stiffener connection parts) to detect whether there are defects such as pores and cracks inside the components; For components that pass the test, subsequent heat treatment is carried out as required to further optimize the uniformity of the structure, improve the mechanical properties, and complete the final preparation.

[0007] Furthermore, in step 1), the division of the loading area follows the principle of "fitting the component structure and matching the service stress": Aircraft wing rib components are divided into the wing rib main body area, the variable cross-section transition area, the stiffener area, and the wing rib connection hole area, among which the variable cross-section transition area and the stiffener area are the key loading areas; The rocket support structure is divided into the main support area, the variable cross-section support area, and the area where the reinforcing ribs intersect. Among them, the variable cross-section support area and the area where the reinforcing ribs intersect are the key loading areas.

[0008] Furthermore, in step 1), the key loading area: the loading direction is consistent with the service force direction of the area, the loading timing adopts the collaborative mode of "additive manufacturing and loading at the same time", the loading force is 15-30 kN, and the loading rate is 0.1-0.3 kN / s; Non-critical loading areas: The loading direction is consistent with the service force direction of the area. The loading timing adopts the "interlayer loading" mode to ensure the balance between loading effect and forming efficiency. The loading force is 5-15 kN and the loading rate is 0.3-0.5 kN / s.

[0009] Furthermore, in step 1), the deformation allocation adopts the strategy of "precisely controlling the shape of the critical loading area and moderately releasing the deformation of the non-critical loading area". The deformation of the critical loading area is controlled at 0.05%-0.15%, and the deformation of the non-critical loading area is controlled at 0.15%-0.3%.

[0010] Furthermore, in step 2), the multi-directional loading system includes a multi-directional loading actuator capable of loading in the X, Y, and Z directions and at any angle, and is equipped with an adjustable loading head that can adjust the angle and contact area of ​​the loading head according to the structural characteristics of different areas of the component, so as to avoid damage to the surface of the component during the loading process.

[0011] Furthermore, in step 2), the temperature monitoring system uses an infrared thermal imager, which can capture the temperature field of the molten pool and the temperature gradient changes of the printed surface in real time, and accurately reflect the temperature status of each area of ​​the component.

[0012] Furthermore, in step 2), the deformation monitoring system uses a laser displacement sensor to collect deformation data of each area of ​​the component in real time, with a data acquisition frequency of not less than 10Hz, so as to achieve real-time and accurate capture of deformation data.

[0013] Furthermore, in step 2), the tooling fixture adopts a high-temperature resistant and adjustable structure to adapt to large magnesium alloy aerospace components of different sizes and structures, ensuring fixing reliability and positioning accuracy.

[0014] Furthermore, in step 3), the structural optimization of the key loading area involves rounding the corners of the variable cross-section area and the connection points of the reinforcing ribs.

[0015] Furthermore, in step 3), the layered slicing and arc additive path of the key loading region are as follows: The slice thickness in the variable cross-section region is set gradually, decreasing from the thick-walled region to the thin-walled region, with a slice thickness of 0.8-2.0 mm. The path planning adopts a spiral gradual path to reduce thermal stress concentration. The thickness of the slices in the reinforcing rib area is 0.8-1.2mm, and the path planning adopts parallel superimposed paths to ensure the forming density and structural strength of the reinforcing ribs; The layered slicing and arc additive path for non-critical loading regions are as follows: The slice thickness for non-critical loading areas is 1.5-2.0 mm, and a general parallel path is used for path planning.

[0016] Furthermore, in step 3), the additive manufacturing sequence is planned as follows: first, non-critical loading areas are added, then variable cross-section transition areas are added, and finally, reinforcing rib areas are added. The critical loading areas adopt the "adding while loading" mode, and the non-critical loading areas adopt the "interlayer loading" mode.

[0017] Furthermore, in step 4), the magnesium alloy wire is selected from Mg-Gd-Y-Zn-Zr series magnesium alloy wire with a diameter of 1.2-1.8mm, preferably Mg-8.5Gd-4Y-2Zn-0.5Zr or Mg-10Gd-3Y-1Zn-0.5Zr alloy wire, which is suitable for the high strength and high toughness requirements of the aerospace field.

[0018] Furthermore, in step 4), the arc additive manufacturing parameters are as follows: welding current is 120-200A, welding speed is 150-250mm / min, wire feed speed is 160-300cm / min, inert shielding gas is argon with a purity ≥99.99%, gas delivery rate is 20-35L / min, and interpass cooling time is 60-180s.

[0019] Furthermore, in step 5), for non-critical areas, a combination of conventional additive manufacturing and light multi-directional loading is used. The light multi-directional loading, i.e., the loading force is controlled at 5-15kN, mainly serves to offset the thermal stress of additive manufacturing and reduce overall deformation. Critical loading region, among which, Variable cross-section region: Multi-directional collaborative loading is carried out simultaneously during the additive manufacturing process. The loading force and loading direction are precisely controlled according to the deformation distribution parameters to alleviate stress concentration in the variable cross-section region, avoid deformation and cracking, and ensure a smooth transition of the variable cross-section. Reinforcing rib area: When additive manufacturing reaches the connection between the reinforcing rib and the main component, directional loading is applied to strengthen the interlayer bond, reduce defects at the connection point, and control the amount of deformation to ensure the positional accuracy of the reinforcing rib and the structural strength.

[0020] Furthermore, in step 5), during the forming process, the temperature of each area is monitored in real time by a temperature monitoring system to control the interlayer temperature between 150-250℃. The deformation data of each area is collected in real time by a deformation monitoring system. If the deformation exceeds the preset range, the loading parameters and additive parameters are adjusted in real time to ensure forming accuracy.

[0021] Furthermore, the strategy for adjusting loading and additive parameters is as follows: when the deformation exceeds the preset upper limit, first increase the loading force in the corresponding area by 5%-10% and reduce the loading rate by 0.05-0.1kN / s. If the deformation is not suppressed, then reduce the welding speed by 10%-20% and shorten the interlayer cooling time by 10-30s. When the detected deformation is below the preset lower limit, first reduce the loading force in the corresponding area by 5%-10% and increase the loading rate by 0.05-0.1kN / s. If the deformation still does not meet the standard, then increase the welding speed by 10%-20% and extend the interlayer cooling time by 10-30s to achieve real-time closed-loop control of deformation.

[0022] Furthermore, in step 8), the subsequent heat treatment employs a combination of solution treatment and aging treatment, wherein... Solution treatment temperature 480-520℃, holding time 2-4h, cooling method is water quenching; The aging temperature is 180-220℃, the holding time is 8-12h, and then cooled to room temperature to further refine the grains, regulate the distribution of the strengthening phase, and improve the mechanical properties and service reliability of the components.

[0023] Furthermore, the method is applicable to the forming of aerospace structural components with variable cross-sections and stiffener structures.

[0024] Furthermore, the aerospace structural components with variable cross-sections and stiffening ribs include, but are not limited to, aircraft wing ribs or rocket supports.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The core innovation of this invention lies in the deep integration of general electric arc additive manufacturing process with the manufacturing requirements of specific high-value aerospace components such as aircraft wing ribs and rocket brackets. Targeting the structural characteristics of components such as variable cross-sections and reinforcing ribs, a zoned loading strategy and deformation distribution scheme are designed to achieve "process-adapted products and precise performance control". This effectively protects specific application scenarios, solves the problem that existing general processes cannot meet the high-requirement forming of specific components, and enhances the application value and protection of the patent.

[0026] 2. It realizes the integrated synergy of electric arc additive manufacturing and multi-directional loading, breaking the traditional process of separate additive manufacturing, stress control, and deformation correction. Through the collaborative operation of "adding while loading", it can offset the uneven thermal stress generated during the additive manufacturing process in real time, accurately control the deformation of the component, and effectively solve the defects such as deformation, cracking, and poor interlayer bonding that occur in the forming process of large magnesium alloy components. The forming accuracy of the component is improved by more than 30%, and the defect rate is reduced by more than 80%, meeting the high precision requirements of the aerospace field.

[0027] 3. Based on the structural characteristics and service requirements of different regions of the component (critical loading region and non-critical loading region), a differentiated zonal loading strategy and additive path planning are adopted to make the structure of key parts of the component (variable cross-section region and stiffener connection part) more uniform and the stress distribution more reasonable, and the mechanical properties are significantly improved: Compared with the components prepared by traditional additive manufacturing process, the components prepared by this invention have a 25%-40% increase in tensile strength, a 20%-35% increase in yield strength, and a fatigue life extension of more than 50%, which can fully meet the service requirements of key components such as aircraft wing ribs and rocket supports.

[0028] 4. It simplifies the manufacturing process by integrating additive manufacturing, stress control, and deformation optimization into one process, eliminating the need for a separate deformation correction process and shortening the manufacturing cycle by 40%-60%. At the same time, the high material utilization rate of arc additive manufacturing technology (up to 90% or more), combined with path planning, reduces raw material waste and lowers manufacturing costs. Compared with the traditional casting + forging process, the manufacturing cost can be reduced by 30%-50%, showing good prospects for engineering applications.

[0029] 5. It has strong process adaptability. It can flexibly adjust the zonal loading strategy, deformation distribution parameters and electric arc additive parameters according to the structural characteristics and service requirements of large magnesium alloy aerospace structural components of different types and sizes. It does not require the replacement of large equipment and tooling. It has a wide range of applications and can be promoted for the manufacturing of various large magnesium alloy aerospace components with complex structures. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments. Taking the forming of aircraft wing ribs (with typical variable cross-section and densely reinforced rib structure) and rocket supports as examples, the specific implementation process of the present invention is illustrated. Example 1 (Conventional general-purpose electric arc additive manufacturing process, blank control group)

[0031] This embodiment employs a conventional electric arc additive manufacturing process, without multi-directional loading and path planning, and utilizes existing traditional processes to compare with the technological advantages of this invention. The specific steps are as follows: The first step is to obtain a three-dimensional model of the aircraft wing ribs, without performing structural optimization or zoning planning, and using conventional general process solutions; The second step is to set up a conventional tungsten inert gas welding (GTAW) additive manufacturing equipment and fix the Mg-8.5Gd-4Y-2Zn-0.5Zr alloy substrate on the worktable using ordinary tooling fixtures. The third step is to use 3D modeling software to export the 3D model of the rib, import it into slicing software for uniform slicing (slice thickness 1.5mm), and use general parallel path planning without distinguishing between variable cross sections and stiffener areas. The fourth step involves selecting Mg-8.5Gd-4Y-2Zn-0.5Zr alloy wire with a diameter of 1.4mm, and grinding and degreasing the surface. Additive manufacturing parameters are set as follows: welding current 160A, welding speed 200mm / min, wire feed speed 220cm / min, argon gas (99.99% purity) supply rate 25L / min, and interpass cooling time 120s. No loading parameters are set, and no loading operation is performed. The fifth step is to start the equipment to add material layer by layer. After each layer is formed, the surface oxides and waste residue are removed with a steel brush. No deformation monitoring or correction is performed. Step 6: After additive manufacturing is completed, the component is placed in an air environment to cool to room temperature, the fixture is removed, excess material is removed by wire cutting, and the surface is polished to complete the preparation. The seventh step is to conduct non-destructive testing and performance testing on the components.

[0032] Performance test results: The component has poor forming accuracy, with significant deformation in the variable cross-section area (deformation amount 0.42%), slight cracking and incomplete penetration defects at the connection between the stiffener and the main body, and a cross-sectional porosity of 1.5%; surface hardness 128HV, tensile strength 312MPa, yield strength 285MPa, fatigue life (under 120MPa stress) 1.5×10 5 Secondly, the structure of key parts of the component (variable cross-section, stiffener connection) is uneven, with obvious stress concentration, which cannot meet the service requirements of the aircraft wing rib. Example 2 (Arc Additive Manufacturing + Unidirectional Loading Process)

[0033] This embodiment employs a process combining electric arc additive manufacturing and unidirectional loading, without performing zone loading and path planning. Compared to the advantages of the multidirectional loading and path planning process of this invention, the specific steps are as follows: Steps one through four are basically the same as in Example 1, except that: an electric arc additive manufacturing-unidirectional loading device is built, unidirectional loading parameters are set (loading force 15kN, deformation 0.2%), and a general path planning is adopted without distinguishing component areas; The fifth step is to start the equipment to add material layer by layer, and simultaneously perform unidirectional loading (the loading direction is fixed to the Z direction). After each layer is formed, use a steel brush to remove surface oxides and waste residue, and use a laser deformation monitoring system to monitor deformation without adjusting parameters. Steps six and seven are exactly the same as in Example 1, completing the preparation and performance testing.

[0034] Performance test results: The forming accuracy of the component has improved, and the overall deformation has decreased to 0.28%. However, there is still significant stress concentration in the variable cross-section area, and a small number of porosity defects remain at the joints of the stiffeners (cross-sectional porosity 0.8%). The surface hardness is 145 HV, the tensile strength is 358 MPa, the yield strength is 320 MPa, and the fatigue life (under 120 MPa stress) is 2.6 × 10⁻⁶. 5 Secondly, the uniformity of the structure in key parts of the component is generally poor, and unidirectional loading cannot adapt to the multidirectional stress characteristics of the component, so the mechanical properties still do not meet the requirements of the aircraft wing rib. Example 3 (Integrated process group of the present invention, aircraft wing rib forming)

[0035] This embodiment employs the forming method of the present invention, and designs a process scheme based on the characteristics of the variable cross-section and densely reinforced structure of aircraft wing ribs. The specific steps are as follows: The first step is structural analysis and process planning of components: obtain the three-dimensional model of the aircraft wing rib and clarify its structural characteristics: the main body of the wing rib is a thin-walled structure with two variable cross-section transition areas (transition slope 15°-30°), and there are 6 dense stiffeners (width 8mm, height 12mm). The connection between the stiffener and the main body is a stress concentration area. Division of regions: critical stress areas (variable cross-section transition areas, stiffener connection areas), non-critical stress areas (non-stress areas of the wing rib main body); Develop a process plan: control the deformation of critical stress areas to 0.08%-0.12%, and the deformation of non-critical stress areas to 0.2%-0.25%; The loading direction in the variable cross-section region is X+Z (to adapt to the service stress direction), with a loading force of 12-18kN and a loading rate of 0.2-0.3kN / s; The loading direction in the stiffener connection area is Y+Z, with a loading force of 8-12kN and a loading rate of 0.1-0.2kN / s; The loading force for non-critical areas is 5-8 kN, and the loading rate is 0.3-0.4 kN / s; The second step is equipment debugging and tooling preparation: Assemble the integrated arc additive manufacturing and multi-directional loading equipment, equipped with an adjustable loading head and tooling fixtures, and fix the Mg-8.5Gd-4Y-2Zn-0.5Zr alloy substrate onto the tooling, controlling the positioning accuracy within ±0.1mm; debug the arc additive manufacturing system, multi-directional loading system, temperature monitoring system (infrared thermal imager), and deformation monitoring system (laser displacement sensor) to ensure normal equipment operation; The third step, 3D modeling and path planning: Optimize the 3D model of the aircraft wing ribs, and optimize the fillets of the variable cross-section transition area and the connection of the stiffeners to reduce stress concentration; Import the slicing software. For the variable cross-section area, use a gradient slice (thickness 1.0-1.5mm, gradually decreasing from thick wall to thin wall) with a spiral gradient path. For the stiffener area, the slice thickness is 1.0mm with a parallel superimposed path. For the non-critical areas of the wing rib body, the slice thickness is 1.5mm with a general parallel path. Plan the additive manufacturing sequence: first, add the non-critical areas of the wing rib body, then add the variable cross-section transition area, and finally add the stiffener area. For the critical areas, use the "adding while loading" mode. Step 4, Material preparation and parameter setting: Select Mg-8.5Gd-4Y-2Zn-0.5Zr alloy wire with a diameter of 1.4mm, and perform surface grinding and degreasing treatment; Additive manufacturing parameters are set as follows: welding current 160A, welding speed 200mm / min (reduced to 180mm / min in the variable cross-section region), wire feed speed 220cm / min, argon gas (99.99% purity) supply rate 25L / min, and interpass cooling time 120s. Set the loading parameters: 12-18kN loading force in the variable cross-section area, 0.08%-0.12% deformation, X+Z loading direction, and 0.3kN / s loading rate; The load on the stiffener connection area is 8-12kN, the deformation is 0.10%-0.12%, the loading direction is Y+Z, and the loading rate is 0.2kN / s. The non-critical area is subjected to a loading force of 5-8 kN, with a deformation of 0.2%-0.25%, in the Z direction, and a loading rate of 0.4 kN / s. Step 5, Integrated forming operation: Turn on the equipment and carry out collaborative operations according to the planned additive manufacturing sequence and loading strategy. For variable cross-section areas and reinforcing rib connection areas, "adding and loading simultaneously" is used, while "interlayer loading" is used for non-critical areas. The temperature monitoring system monitors the interlayer temperature in real time and controls it between 180-220℃. The deformation monitoring system collects deformation data of each area in real time. If the deformation exceeds the preset range, the loading force and additive manufacturing speed are automatically adjusted according to the control strategy. Step 6, interlayer treatment: After each layer of additive manufacturing and loading is completed, use a steel brush to remove surface oxides and waste residue, perform local grinding at the joints of variable cross sections and stiffeners, and correct the deformation of areas exceeding the standard in real time; Step 7, Post-forming processing: After additive manufacturing and loading are completed, keep the tooling fixed, slowly cool to room temperature, remove the fixture, and remove excess material by wire cutting. Step 8, subsequent optimization: surface grinding and polishing, ultrasonic testing and radiographic testing of key areas; solution treatment (500℃, 3h, water quenching) + aging treatment (200℃, 10h), cooling to room temperature to complete preparation.

[0036] Performance test results: The component exhibits excellent forming accuracy, with an overall deformation of 0.15%, and deformation in key areas controlled within 0.12%. There are no defects such as deformation, cracking, or incomplete interlayer welding. The cross-sectional porosity is reduced to 0.2%. The surface hardness is 186 HV, tensile strength is 415 MPa, yield strength is 378 MPa, and fatigue life (at 120 MPa stress) is 5.8 × 10⁻⁶. 5 The components exhibit uniform microstructure across all regions, reasonable stress distribution in key areas, and uniform distribution of reinforcing phases, fully meeting the aerospace service requirements for aircraft wing ribs. Compared to Example 1, the forming accuracy is improved by 64%, tensile strength by 33%, and fatigue life by 2.9 times; compared to Example 2, the forming accuracy is improved by 46%, tensile strength by 16%, and fatigue life by 1.2 times, highlighting the significant advantages of the integrated process of this invention. Example 4 (Integrated process assembly of the present invention, rocket bracket forming)

[0037] This embodiment employs the forming method of the present invention. Taking into account the structural characteristics of the rocket support (which has a variable cross-section support area and a reinforcing rib intersection area), the zonal loading strategy and parameters are adjusted to achieve the forming process. The specific steps are as follows: The first step is structural analysis and process planning of components: obtain a three-dimensional model of the rocket support and clarify its structural characteristics: the main body of the support is a thick-walled structure, the bottom is a variable cross-section support area (transition slope 20°-45°), and the top has a convergence area of ​​4 reinforcing ribs (severe stress concentration). Divide the critical stress area (variable cross-section support area, stiffener intersection area) into the non-critical stress area (middle of the support body). Develop a process plan: control the deformation in critical areas to 0.05%-0.10%, and the deformation in non-critical areas to 0.25%-0.30%; The variable cross-section support area is loaded in the X+Y+Z direction, with a loading force of 20-30kN and a loading rate of 0.1-0.2kN / s; The loading direction in the area where the stiffeners intersect is multi-directional synergistic loading (X+Y direction), with a loading force of 15-25kN and a loading rate of 0.15-0.2kN / s; The loading force for non-critical areas is 10-15 kN, and the loading rate is 0.4-0.5 kN / s; Steps two through eight are basically the same as in Example 3, except that the tooling fixture is adjusted to fit the size of the rocket bracket. Slicing and path planning: The slice thickness in the variable cross-section support area is 1.2-2.0mm (gradual setting), and the slice thickness in the stiffener intersection area is 0.8mm; Additive parameters: welding current 180A, welding speed 180mm / min, wire feed speed 250cm / min, argon gas supply speed 30L / min, interpass cooling time 150s; Loading parameters: 20-30kN loading force in the variable cross-section support area, 0.05%-0.10% deformation, and 0.2kN / s loading rate; The loading force at the intersection of the reinforcing ribs is 15-25kN, the deformation is 0.08%-0.10%, and the loading rate is 0.15kN / s. The loading force for non-critical areas is 10-15 kN, the deformation is 0.25%-0.30%, and the loading rate is 0.5 kN / s. The subsequent heat treatment parameters remain unchanged.

[0038] Performance test results: The component has high forming accuracy, with an overall deformation of 0.18%, and the deformation in key areas is controlled within 0.10%. There are no forming defects, and the cross-sectional porosity is 0.15%. The surface hardness is 192 HV, the tensile strength is 432 MPa, the yield strength is 395 MPa, and the fatigue life (under 150 MPa stress) is 4.9 × 10⁻⁶. 5 The mechanical properties of key components are excellent, and the stress distribution is uniform, fully meeting the service requirements of rocket supports, proving that the method of this invention can be adapted to the forming requirements of different types of large magnesium alloy aerospace structural components.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for integrated arc additive manufacturing and multi-directional loading forming of large magnesium alloy aerospace structural components, characterized in that, Includes the following steps: 1) Component structural analysis and process planning: Obtain the three-dimensional model of the target component, clarify its structural characteristics, divide the critical loading area and non-critical loading area, and formulate a zoned loading strategy and deformation distribution scheme; 2) Equipment debugging and tooling preparation: Set up an integrated arc additive manufacturing-multi-directional loading equipment, and fix the magnesium alloy substrate with tooling fixtures to ensure accurate positioning; 3) 3D modeling and path planning: Optimize the 3D model, perform layer slicing, and plan the arc additive manufacturing path; combine with the partitioned loading strategy to plan the additive manufacturing sequence and loading timing of each region, so as to achieve the coordinated operation of additive manufacturing and loading; 4) Material preparation and parameter setting: High-strength magnesium alloy wire was selected, and the parameters for electric arc additive manufacturing and multi-directional loading were set. 5) Integrated forming operation: Turn on the integrated arc additive manufacturing-multi-directional loading equipment, and carry out layer-by-layer additive manufacturing and multi-directional loading collaborative operation according to the planned additive manufacturing path and loading strategy; 6) Interlayer treatment: Remove surface oxides, perform localized polishing, and correct deformation in real time; 7) Post-forming processing: Slowly cool to room temperature, remove excess material, and obtain the target component; 8) Subsequent optimization: Non-destructive testing and heat treatment are performed on key parts to improve mechanical properties.

2. The forming method according to claim 1, characterized in that, In step 1), the division of the loading area follows the principle of "fitting the component structure and matching the service stress": Aircraft wing rib components are divided into the wing rib main body area, the variable cross-section transition area, the stiffener area, and the wing rib connection hole area, among which the variable cross-section transition area and the stiffener area are the key loading areas; The rocket support structure is divided into the main support area, the variable cross-section support area, and the area where the reinforcing ribs intersect. Among them, the variable cross-section support area and the area where the reinforcing ribs intersect are the key loading areas.

3. The forming method according to claim 2, characterized in that, In step 1), the key loading area is loaded in the same direction as the service stress direction of the area. The loading timing adopts a collaborative mode of "additive manufacturing and loading at the same time". The loading force is 15-30 kN and the loading rate is 0.1-0.3 kN / s. Non-critical loading areas: The loading direction is consistent with the service force direction of the area. The loading timing adopts the "interlayer loading" mode to ensure the balance between loading effect and forming efficiency. The loading force is 5-15 kN and the loading rate is 0.3-0.5 kN / s.

4. The forming method according to claim 2, characterized in that, In step 1), the deformation allocation adopts the strategy of "precise control of the shape in the critical loading area and moderate release in the non-critical loading area". The deformation of the critical loading area is controlled at 0.05%-0.15%, and the deformation of the non-critical loading area is controlled at 0.15%-0.3%.

5. The forming method according to claim 2, characterized in that, In step 3), the layered slicing and arc additive path of the key loading region are as follows: The slice thickness in the variable cross-section region is set gradually, decreasing from the thick-walled region to the thin-walled region, with a slice thickness of 0.8-2.0 mm. The path planning adopts a spiral gradual path to reduce thermal stress concentration. The thickness of the slices in the reinforcing rib area is 0.8-1.2mm, and the path planning adopts parallel superimposed paths to ensure the forming density and structural strength of the reinforcing ribs; The layered slicing and arc additive path for non-critical loading regions are as follows: The slice thickness for non-critical loading areas is 1.5-2.0 mm, and a general parallel path is used for path planning.

6. The forming method according to claim 2, characterized in that, In step 3), the additive manufacturing sequence is planned as follows: first, non-critical loading areas are added, then variable cross-section transition areas are added, and finally, reinforcing rib areas are added. The critical loading areas adopt the "adding while loading" mode, and the non-critical loading areas adopt the "interlayer loading" mode.

7. The forming method according to claim 1, characterized in that, In step 4), the magnesium alloy wire is selected from Mg-Gd-Y-Zn-Zr series magnesium alloy wire with a diameter of 1.2-1.8mm, preferably Mg-8.5Gd-4Y-2Zn-0.5Zr or Mg-10Gd-3Y-1Zn-0.5Zr alloy wire, which is suitable for the high strength and high toughness requirements of the aerospace field.

8. The forming method according to claim 1, characterized in that, In step 4), the arc additive manufacturing parameters are as follows: welding current is 120-200A, welding speed is 150-250mm / min, wire feed speed is 160-300cm / min, inert shielding gas is argon with a purity of ≥99.99%, gas supply speed is 20-35L / min, and interpass cooling time is 60-180s.

9. The forming method according to claim 1, characterized in that, In step 8), the subsequent heat treatment employs a combination of solution treatment and aging treatment, wherein... Solution treatment temperature 480-520℃, holding time 2-4h, cooling method is water quenching; Aging temperature 180-220℃, heat preservation time 8-12h, cool to room temperature.

10. The forming method according to claim 1, characterized in that, The method is applicable to the forming of aerospace structural components with variable cross-sections and stiffeners.