Composite shot peening method for an aeronautical load-bearing structure

Abstract

This application discloses a composite shot peening strengthening method for aerospace load-bearing structural components. The method includes dividing the shape-dependent regions or areas with high tensile stress distribution of the aerospace load-bearing structural components into regions and designing composite shot peening paths; designing process parameters for CNC mechanical microparticle shot peening and laser shot peening; performing CNC mechanical microparticle shot peening and laser shot peening; and finally, inspecting the shot peening strengthening quality of the aerospace load-bearing structural components. This application provides a composite shot peening strengthening method for aerospace load-bearing structural components, which can achieve composite shot peening strengthening of aerospace load-bearing structural components, increasing the residual compressive stress layer on the surface of the structural components while reducing surface roughness, effectively and quickly realizing composite shot peening strengthening of load-bearing structural components.

Description

Technical Field

[0001] This invention relates to the field of shot peening forming technology for aerospace panels, and specifically to a composite shot peening strengthening method for aerospace load-bearing structural components. Background Technology

[0002] In traditional aircraft manufacturing, the technical requirements for load-bearing structural components (such as residual compressive stress and surface quality) are high. Traditional strengthening methods for these components include rolling, grinding, and mechanical shot peening. However, due to the significant stress concentration, fatigue damage, and corrosion damage associated with these components, the strengthening requirements are quite stringent. Strengthening demands include a deep residual compressive stress layer, finer surface micrograins, and lower surface roughness. Laser shot peening and CNC mechanical microparticle shot peening are commonly used strengthening processes in aircraft manufacturing, but they have the following problems:

[0003] 1. Laser shot peening can produce a residual compressive stress layer with a large value and thickness in aerospace load-bearing structural components, but the surface roughness will be greatly increased, and the surface grain refinement and dislocation density will be low.

[0004] 2. CNC mechanical micro-particle shot peening can achieve better grain refinement, higher dislocation density layer and reduced surface roughness on the surface of aerospace load-bearing structural components. However, the thickness of the residual compressive stress layer on the surface is very thin and the residual compressive stress value is low.

[0005] Therefore, this application proposes a composite shot peening strengthening method for aerospace load-bearing structural components to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of traditional reinforcement processes for aerospace load-bearing structural components, this application provides a composite shot peening reinforcement method for aerospace load-bearing structural components. This method can increase the residual compressive stress layer on the surface of the structural component while reducing the surface roughness, thus effectively and quickly achieving composite shot peening reinforcement of load-bearing structural components.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A composite shot peening strengthening method for aerospace load-bearing structural components includes the following steps:

[0009] S1. Analyze the structural characteristics, material properties, and working stress distribution of aerospace load-bearing structural components;

[0010] S2. Based on the analysis results, the shape fusion area or the area with large tensile stress distribution of the aerospace load-bearing structural component is divided into regions and a composite shot peening path is designed, including the laser shot peening area and the CNC mechanical microparticle shot peening area. The CNC mechanical microparticle shot peening area is located inside the laser shot peening area.

[0011] The overlapping area of ​​the laser peening area and the CNC mechanical particle peening area forms a composite peening strengthening zone.

[0012] S3. Design the process parameters for CNC mechanical micro-particle shot peening and laser shot peening;

[0013] S4. Laser shot peening is performed on the aerospace load-bearing structural components in the laser shot peening area.

[0014] S5. In the CNC mechanical micro-powder shot peening area, the aerospace load-bearing structural components are strengthened by CNC mechanical micro-powder shot peening.

[0015] S6. Perform shot peening strengthening quality inspection on the aerospace load-bearing structural components. If the strengthening quality in the composite shot peening strengthening zone is insufficient, repeat steps S4 and / or S5.

[0016] As a preferred embodiment, the specific method for dividing the region with larger tensile stress distribution in S2 is as follows:

[0017] Areas in aerospace load-bearing structural components where the local stress is 2-3 times greater than the nominal stress are designated as laser shot peening areas.

[0018] Areas in aerospace load-bearing structural components where the local stress exceeds 3-5 times the nominal stress are designated as CNC mechanical microparticle shot peening areas.

[0019] Preferably, in S2, the shape fusion region includes areas of abrupt size changes, holes, grooves, slots, constraint boundaries, or sharp corners. The specific method for dividing this region is as follows:

[0020] The shape fusion region is divided into a composite shot peening reinforcement zone.

[0021] Preferably, in S3, the process parameters include laser spot size, laser energy, laser pulse, laser overlap rate, particle shot size, particle shot peening intensity, particle shot material, shot coverage and / or shot peening angle.

[0022] As a preferred option, CNC micro-peening has a coverage rate of 100%-200%, while laser peening has an overlap rate of 50%-80%.

[0023] As a preferred option, in S2, the composite shot peening path is as follows:

[0024] In the laser peening process, the peening begins at the working tensile stress area; in the CNC microparticle peening process, the peening proceeds from the edge of the laser peening area toward the other edge of the laser peening area on the surface of the structural component.

[0025] Preferably, a pretreatment step is also included, specifically...

[0026] Protective and cleaning treatments are applied to the load-bearing structural components of aerospace equipment. Black tape is applied to the laser shot-peened area as an absorption layer during laser processing, and protective tape is applied to the CNC machine particulate shot-peened area.

[0027] As an alternative, it also includes constructing a database of composite shot peening strengthening effects. The database establishes matching laser shot peening process parameters and microparticle shot peening process parameters for aerospace load-bearing structural components made of different materials, and can output the residual stress distribution, surface roughness distribution, and hardness distribution required for aerospace load-bearing structural components made of different materials.

[0028] As a preferred option, for 2024-T351 aluminum alloy, when the laser spot diameter is 3mm, the laser energy is 8J, the pulse is 20ns, the particle shot diameter is 0.1mm, and the shot peening intensity is 0.1mmA, the residual compressive stress layer in the composite shot peening area can reach a maximum of 1mm, and the surface roughness is less than 50μm.

[0029] As a preferred option, S6 is specifically...

[0030] If the residual compressive stress layer test fails to meet the standard, repeat step S4;

[0031] If the surface roughness test fails to meet the standard, repeat step S5;

[0032] If the residual compressive stress layer and surface roughness test both fail to meet the standards, repeat steps S4-S5.

[0033] The present invention has the following beneficial effects:

[0034] 1. This invention provides a composite shot peening strengthening method for aerospace load-bearing structural components, which can realize the strengthening processing of aerospace load-bearing structural components. At the same time, based on the analysis of the wall panel structure and combined with this method, composite shot peening processing of aerospace structural components of various sizes and materials can be realized.

[0035] 2. Compared with the prior art, the present invention can quickly plan the composite shot peening area and shot peening path of the structural component by analyzing the stress distribution and structural characteristics of the load-bearing structural component, and quickly design the composite shot peening process of the load-bearing structural component, thus saving design process and processing time.

[0036] 3. This invention combines laser shot peening and micro-particle shot peening for composite shot peening of load-bearing structural components. It also combines processing quality inspection to quickly perform re-peening and other operations, which can quickly complete the strengthening processing of load-bearing structural components, improve the surface quality of structural components, and control the strengthening quality error to keep it within a certain range. Attached Figure Description

[0037] Figure 1 This is a flowchart of the method of the present invention.

[0038] Figure 2 This is a schematic diagram of composite shot peening.

[0039] Figure 3 This is a schematic diagram of the composite shot peening path.

[0040] Among them, (a) is the sample to be strengthened, (b) is the laser shot peening path planning, (c) is the particle shot peening path planning, and (d) is the sample after composite shot peening strengthening.

[0041] Figure 4 The diagram shows the residual stress distribution of the cross section of 2J aluminum alloy 2J laser shot peening with a thickness of 3mm.

[0042] Figure 5 This is a cross-sectional view of a 2J laser-peened 2J aluminum alloy with a thickness of 3mm and a particle peening effect of 0.1mmA.

[0043] Among them, S11 is the residual stress distribution map, SDV1 is the surface grain refinement map, and SDV3 is the surface dislocation density distribution map. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0045] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," 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 invention 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. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0046] like Figures 1-5 As shown, a composite shot peening strengthening method for aerospace load-bearing structural components includes...

[0047] S1. Analyze the structural characteristics, material properties, and working stress distribution of aerospace load-bearing structural components.

[0048] S2. Based on the analysis results, the shape-concentrated areas (stress concentration areas) or areas with large tensile stress distribution of aerospace load-bearing structural components are divided into regions and composite shot peening paths are designed, including laser shot peening areas and CNC mechanical particle shot peening areas. The CNC mechanical particle shot peening area is located inside the laser shot peening area; the overlap of the laser shot peening area and the CNC mechanical particle shot peening area forms a composite shot peening strengthening zone.

[0049] The specific method for dividing areas with large tensile stress distribution is as follows:

[0050] Areas in aerospace load-bearing structural components where the local stress exceeds the nominal stress by 2-3 times are designated as laser shot peening areas; areas in aerospace load-bearing structural components where the local stress exceeds the nominal stress by 3-5 times are designated as CNC mechanical particle shot peening areas.

[0051] The shape fusion region includes areas with abrupt changes in size, holes, grooves, slots, constraint boundaries, or sharp corners. The specific division method is as follows: the shape fusion region is divided into a composite shot peening reinforcement zone.

[0052] The composite shot peening path is as follows: during laser shot peening, shot peening starts from the working tensile stress area; during CNC microparticle shot peening, shot peening proceeds from the edge of the laser shot peening area to the other edge of the laser shot peening area on the surface of the structural component.

[0053] S3. Design the process parameters for CNC mechanical microparticle shot peening and laser shot peening.

[0054] Based on the parameter analysis, the strengthening processing requirements of the aerospace load-bearing structural components are determined. According to the working stress distribution and material of the structural components, the composite shot peening strengthening process parameters (laser spot size, laser energy, laser pulse, laser overlap rate, particle shot size, particle shot peening intensity, particle shot material, shot coverage and shot peening angle, etc.) are designed for the surface of the aerospace structural components.

[0055] S4. The aerospace load-bearing structural components are clamped onto the industrial robot using specialized fixtures. In the laser shot peening area, the aerospace load-bearing structural components are subjected to laser shot peening strengthening processing using a laser shot peening system.

[0056] S5. After laser shot peening is completed, the aerospace welded structural parts are clamped in the processing area of ​​the micro-particle shot peening CNC machine tool using a professional fixture. In the CNC micro-particle shot peening area, the CNC shot peening system performs composite shot peening on the area that has been laser-processed through micro-particle shot peening.

[0057] S6. After completing laser shot peening and CNC micro-particle shot peening, perform shot peening quality inspection on the aerospace load-bearing structural components. If the strengthening quality in the composite shot peening area is insufficient, repeat steps S4 and / or S5 again. After checking that the surface quality (roughness, contour, etc.) meets the requirements, deliver the component. Specifically, if the residual compressive stress layer test fails, repeat step S4; if the surface roughness test fails, repeat step S5; if both the residual compressive stress layer and surface roughness tests fail, repeat steps S4-S5.

[0058] This application also includes the construction of a composite shot peening strengthening effect database. For aerospace load-bearing structural components made of different materials, the database establishes matching laser shot peening process parameters and micro-particle shot peening process parameters, capable of outputting the required residual stress distribution, surface roughness distribution, and hardness distribution for aerospace load-bearing structural components made of different materials. Furthermore, based on the composite shot peening strengthening effect database, CNC shot peening and laser shot peening process parameters are designed in reverse, with CNC micro-particle shot peening coverage of 100%-200% and laser shot peening overlap rate of 50%-80%.

[0059] Specialized fixtures are used to hold the load-bearing structural components, ensuring the smooth execution of laser peening and CNC micro-peening strengthening processes. Simultaneously, according to the strengthening process, the areas to be processed on the structural components are adjusted using robots and CNC machine tool fixtures to achieve more flexible clamping and peening. Before laser peening, the load-bearing structural components require protective treatment: the surface is cleaned, and black tape is applied as an absorption layer during laser processing. Protective tape is also applied to areas requiring mechanical peening to protect the areas to be laser-processed during CNC mechanical peening. After laser peening and CNC micro-peening, the protective tape and black tape are removed, the surface is cleaned, and the surface strengthening quality is inspected. Areas with insufficient strengthening are re-peened to meet the requirements of the composite peening process.

[0060] Example 1: Composite shot peening is performed on a 2024-T351 aluminum alloy wall panel with dimensions of 500mm*300mm*3mm, rib height of 20mm, and rib spacing of 150mm. The main steps include:

[0061] After adjusting the specialized fixtures, the structure and stress distribution of the 2024-T351 aluminum alloy panel were analyzed. The panel was divided into laser peening and CNC microparticle peening areas. The laser peening area was then painted with black paint. The panel was clamped in the specialized fixture and moved to the laser peening working area. The laser peening output energy was 8J, the laser spot diameter was set to φ3mm, and the laser pulse was 20ns. The laser peening equipment performed laser peening on the ribbed panel according to the pre-designed process parameters and path. After peening one area, the fixture was adjusted, and the peening process continued to shape the subsequent areas to be processed.

[0062] During laser peening, a specialized fixture holding the aluminum alloy panel is placed in the laser peening work area. The fixture and robot are adjusted to ensure the surface to be processed is perpendicular to the laser beam. Water is supplied to the black-painted surface of the panel through a water pipe (as a constraint layer). The laser beam path proceeds from one side of the area to be processed on the surface of the structural component. After processing one area, the fixture is adjusted, and processing continues on the remaining areas to be laser peened. After laser peening is completed, the structural component is dried, and the specialized fixture is moved to the CNC micro-peening area.

[0063] The specialized fixture is moved to the CNC micro-peening machine's working area, the panel position is adjusted, and CNC micro-peening is performed. After CNC micro-peening is completed, the surface of the reinforced area of ​​the panel is inspected. Areas with insufficient reinforcement are re-peened to improve surface quality. Once the composite peening reinforcement quality meets the requirements, the panel is delivered. The CNC micro-peening path is a "Z" shape, evenly covering the laser peening area.

[0064] Finite element analysis (FEM) simulations of composite shot peening were performed on 2024-T351 aluminum alloy using ABQUAS. The laser shot peening parameters were: laser spot diameter 3 mm, laser energy 2 J, pulse duration 20 ns, and overlap rate 50%. The micro-particle shot peening parameters were: micro-particle diameter 0.1 mm, shot peening intensity 0.1 mmA, nozzle angle 90°, and shot peening coverage 100%. Simulation results showed that the maximum residual compressive stress in the cross-section laser shot peening was -389 MPa, while the maximum residual compressive stress in the cross-section composite shot peening was -817.7 MPa. The thickness of the residual compressive stress layer increased, and the grains in the composite shot peening region were significantly refined, with an increased dislocation density. The simulation results demonstrate that composite shot peening combining laser shot peening and micro-particle shot peening can significantly improve the strengthening effect.

[0065] For 2024-T351 aluminum alloy, when the laser spot diameter is 3mm, the laser energy is 8J, the pulse is 20ns, the particle shot diameter is 0.1mm, and the shot peening intensity is 0.1mmA, the maximum residual compressive stress layer in the composite shot peening area can reach 1mm, and the surface roughness is less than 50μm.

[0066] This application provides a composite shot peening strengthening method for aerospace load-bearing structural components. Based on the load-bearing structural component, in areas of high stress concentration and distribution, a composite shot peening process is designed according to the structural characteristics and shot peening characteristics. Laser shot peening is first performed in these areas, followed by fine particle shot peening. Simultaneously, the shot peening path is scientifically and effectively optimized to ensure that the strengthened shot peening quality meets requirements and the stress distribution of the structural component is more reasonable. This composite shot peening strengthening method can improve the fatigue resistance, surface corrosion resistance, and reduce surface stress concentration of aerospace load-bearing structural components, thereby extending the service life of the structural components.

[0067] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A composite shot peening strengthening method for aerospace load-bearing structural components, characterized in that, Includes the following steps: S1. Analyze the structural characteristics, material properties, and working stress distribution of aerospace load-bearing structural components; S2. Based on the analysis results, the shape fusion area or the area with large tensile stress distribution of the aerospace load-bearing structural component is divided into regions and a composite shot peening path is designed, including the laser shot peening area and the CNC mechanical microparticle shot peening area. The CNC mechanical microparticle shot peening area is located inside the laser shot peening area. The overlapping area of ​​the laser peening area and the CNC mechanical particle peening area forms a composite peening strengthening zone. S3. Design the process parameters for CNC mechanical micro-particle shot peening and laser shot peening; S4. Laser shot peening is performed on the aerospace load-bearing structural components in the laser shot peening area. S5. In the CNC mechanical micro-powder shot peening area, the aerospace load-bearing structural components are strengthened by CNC mechanical micro-powder shot peening. S6. Perform shot peening strengthening quality inspection on the aerospace load-bearing structural components. If the strengthening quality in the composite shot peening strengthening zone is insufficient, repeat steps S4 and / or S5.

2. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, In S2, the specific method for dividing the region with larger tensile stress distribution is as follows: Areas in aerospace load-bearing structural components where the local stress is 2-3 times greater than the nominal stress are designated as laser shot peening areas. Areas in aerospace load-bearing structural components where the local stress exceeds 3-5 times the nominal stress are designated as CNC mechanical microparticle shot peening areas.

3. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, In S2, the shape fusion region includes areas of abrupt size changes, holes, grooves, slots, constraint boundaries, or sharp corners. The specific method for dividing this region is as follows: The shape fusion region is divided into a composite shot peening reinforcement zone.

4. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, In S3, the process parameters include laser spot size, laser energy, laser pulse, laser overlap rate, particle shot size, particle shot peening intensity, particle shot material, shot coverage and / or shot peening angle.

5. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, CNC micro-peening has a coverage rate of 100%-200%, while laser peening has an overlap rate of 50%-80%.

6. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, In S2, the composite shot peening path is: In the laser peening process, the peening begins at the working tensile stress area; in the CNC microparticle peening process, the peening proceeds from the edge of the laser peening area toward the other edge of the laser peening area on the surface of the structural component.

7. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, It also includes a preprocessing step, specifically, Protective and cleaning treatments are applied to the load-bearing structural components of aerospace equipment. Black tape is applied to the laser shot-peened area as an absorption layer during laser processing, and protective tape is applied to the CNC machine particulate shot-peened area.

8. The composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, It also includes building a database of composite shot peening strengthening effects. The database establishes matching laser shot peening process parameters and microparticle shot peening process parameters for aerospace load-bearing structural components made of different materials. It can output the residual stress distribution, surface roughness distribution, and hardness distribution required for aerospace load-bearing structural components made of different materials.

9. A composite shot peening strengthening method for aerospace load-bearing structural components according to claim 4, characterized in that, For 2024-T351 aluminum alloy, when the laser spot diameter is 3mm, the laser energy is 8J, the pulse is 20ns, the particle shot diameter is 0.1mm, and the shot peening intensity is 0.1mmA, the maximum residual compressive stress layer in the composite shot peening area can reach 1mm, and the surface roughness is less than 50μm.

10. A composite shot peening strengthening method for aerospace load-bearing structural components according to claim 1, characterized in that, S6 specifically refers to, If the residual compressive stress layer test fails to meet the standard, repeat step S4; If the surface roughness test fails to meet the standard, repeat step S5; If the residual compressive stress layer and surface roughness test both fail to meet the standards, repeat steps S4-S5.

Images