Composite shot peening strengthening machining method for aviation welding structural part

Abstract

The invention belongs to the field of aeronautical manufacturing, and particularly relates to a composite shot peening strengthening method for an aeronautical welded component, which comprises three parts, namely laser shot peening strengthening, numerical control mechanical shot peening strengthening and sand blasting treatment. The composite shot peening process for composite shot peening strengthening of the aviation welding structural part is designed according to the residual stress distribution characteristics of the welding seam of the aviation welding structural part and the positive and negative residual stress distribution characteristics, and shot peening area division and shot peening path design are carried out on an area to be strengthened of the welding structural part. The aviation welding structural part to be strengthened is clamped on a numerical control mechanical shot blasting machine tool through a special clamp, and shot blasting strengthening machining is conducted on a mechanical shot blasting machining area; and after mechanical shot peening strengthening machining is completed, clamping the aviation welding structural part in a machining area of a laser shot peening system through a special clamp, and carrying out laser shot peening strengthening machining on the divided laser shot peening areas of the component. And after mechanical shot peening and laser shot peening strengthening are completed, the surface quality of the component is checked, surface treatment is conducted on the component through a sand blasting process, and delivery is conducted after it is checked that the requirement is met. According to the composite shot peening strengthening machining method for the aviation welding structural part, shot peening strengthening of the aviation welding structural part can be achieved, the distribution error of production residual stress on the surface of the welding structural part can be smaller than + / -10 MPa through composite shot peening strengthening, and the error of surface roughness is smaller than + / -0.5 micrometer.

Description

Technical Field

[0001] This invention patent relates to the field of strengthening processing of aviation welded structural parts, and specifically relates to a composite shot peening strengthening processing method for aviation welded structural parts. Background Art

[0002] In the field of traditional aircraft manufacturing, the butt weld length of the fuselage skin in aviation welded structural parts is 50 - 300 mm, the fillet weld length of the spar / rib is 20 - 100 mm, and the circumferential weld length of the engine bracket is 200 - 800 mm. The welding stress (normal stress) existing in these welded structural parts seriously affects the fatigue life of the structure. In traditional shot peening strengthening, numerically controlled shot peening forming impacts the strengthening surface by spraying a large number of shot, and large-area plastic deformation occurs on the shot peening surface to achieve panel strengthening. The strengthening efficiency is high, but the degree of plastic strengthening generated by the shot impact is limited; laser peening forming irradiates the absorption layer preset on the forming surface through a high-energy laser beam. The absorption layer generates high-temperature and high-pressure plasma, and the plasma explosion forms a shock wave that propagates towards the panel surface, causing plastic deformation on the forming surface to achieve part strengthening. The degree of plastic strengthening of the forming surface in the laser peening area is high, but it is necessary to peen point by point, and the forming efficiency is relatively low. The depth of the residual compressive stress layer generated by laser peening strengthening is 5 - 10 times that of mechanical shot peening strengthening, and the depth of the residual compressive stress of laser peening strengthening is 2 - 3 times that of mechanical shot peening forming. According to the material and welding stress distribution characteristics of aviation welded structural parts, laser peening strengthening is adopted in the areas with relatively large welding stress, and numerically controlled mechanical shot peening strengthening is adopted in the areas with relatively small welding stress and no welding stress. At the same time, scientific and effective shot peening process design is carried out to make the stress distribution and surface quality of the strengthened welded structural parts meet the requirements.

[0003] The technical solution of combining numerically controlled shot peening strengthening technology and laser peening strengthening technology to process aviation welded structural parts is feasible. Therefore, this invention patent has invented a composite shot peening strengthening processing method for aviation welded structural parts, which is used for the shot peening strengthening processing of aviation welded structural parts. Summary of the Invention

[0004] Aiming at the deficiencies of the traditional strengthening processing technology for aviation welded structural parts, the purpose of this invention patent is to provide a composite shot peening strengthening processing method for aviation welded structural parts, which can effectively and quickly achieve the shot peening strengthening processing of aviation welded structural parts.

[0005] To achieve the above technical tasks, the present invention adopts the following technical solutions:

[0006] A composite shot peening strengthening processing method for aviation welded structural parts, characterized in that the aviation welded structural part includes at least 1 weld seam on the surface of the structural part, and the composite shot peening strengthening of the aviation welded structural part includes the following steps:

[0007] Step 1: According to the structure of the aviation welded structural part, conduct parameter analysis on the weld stress distribution of the structural part and the material of the structural part, etc.

[0008] Step 2: According to the above parameter analysis, determine the strengthening processing tasks of the aviation welded structural part, and design the process parameters of surface composite shot peening for the aviation welded structural part through the weld welding stress distribution of the structural part and according to the structural and material characteristics of the structural part.

[0009] Step 3: Clamp the aviation welded structural part to be strengthened in the working area of the numerically controlled shot peening machine tool by a special fixture, and conduct numerically controlled shot peening strengthening processing on the positions with lower stress distribution and the stress-free surface of the structural part through numerically controlled shot peening.

[0010] Step 4: After the numerically controlled shot peening strengthening processing is completed, clamp the aviation welded structural part in the processing area of the laser shot peening system by a professional fixture, and the laser shot peening system conducts shot peening strengthening processing on the places with larger welding stress distribution such as the weld area through high-energy laser beams.

[0011] Step 5: After the numerically controlled shot peening and laser shot peening strengthening are completed, check the surface quality of the strengthened structural part, conduct shape correction on the surface of the structural part through sandblasting equipment, and deliver it after checking that the surface quality (roughness, profile, etc.) meets the requirements.

[0012] Furthermore, in Step 1, it is also necessary to determine the division of the surface strengthening area of the structural part, the mechanical shot peening area and the laser shot peening area according to the welding process parameters and material characteristics of the welded structural part, and the welding process parameters and material characteristics include: analyzing the weld stress distribution and material characteristics of the welded structural part.

[0013] Furthermore, in Step 2, divide the numerically controlled shot peening and laser into areas according to the surface stress distribution and target strengthening requirements of the welded structural part, and design the process parameters of numerically controlled shot peening and laser shot peening according to the shot peening induced stress method. The coverage rate of numerically controlled shot peening is 20%-50%, and the overlapping rate of laser shot peening is 50%-80%.

[0014] Furthermore, in Step 3, the panel can be clamped in areas according to the designed shot peening process information by a special fixture to ensure the numerically controlled shot peening and laser shot peening forming processing. At the same time, according to the forming processing process, adjust the position of the panel to be processed by the fixture to achieve more flexible clamping and processing.

[0015] Furthermore, in Step 3, the welded structural part needs to be protected before mechanical shot peening strengthening. Stick protective tapes on the areas that need laser shot peening strengthening, which can protect the areas to be laser processed during the numerically controlled mechanical shot peening process; after the mechanical shot peening strengthening is completed, clean the surface of the structural part, remove the protective tape in the laser processing area, and apply black paint as the absorption layer in the laser processing.

[0016] Further, in step 5, after completing laser peening and CNC peening forming, remove the protective tape and black tape on the surface, perform sandblasting on the connection area of the two peening forming to reduce the surface difference between the two areas, and process the out-of-tolerance parts on the surface of the structural member. The sandblasting is carried out from the mechanical peening area to the laser peening area for surface treatment.

[0017] Further, during the laser peening strengthening process, the peening starts from the middle position of the weld seam; during the CNC peening strengthening process, the peening is carried out from the edge of the weld seam towards the edge of the surface of the structural member.

[0018] Further, the welding stress distribution of the aviation welded structural member σ(y): The longitudinal stress at a distance y from the center line of the weld seam, σ max : The maximum tensile stress at the weld center (usually close to the material yield strength σ y ), w: The half-width of the heat-affected zone (HAZ); σ y (x): The transverse stress at a distance x from the end of the weld seam, σ trans : The peak value of the transverse stress, L: The stress attenuation characteristic length.

[0019] During the peening strengthening process, through the composite peening strengthening processing method of the aviation welded structural member, after the composite peening strengthening of the aviation welded structural member, the residual stress distribution error on the surface of the welded component can be made less than ±10 MPa, and the surface roughness error can be less than ±0.5 μm through the composite peening strengthening.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention provides a composite peening strengthening processing method for aviation welded structural members, which can achieve peening strengthening of aviation welded structural members. At the same time, according to the materials of aviation structural members and the welding stress distribution and combining this method, peening strengthening processing of welded structural members of various materials and structural members of different shapes can be achieved.

[0022] 2. Compared with the prior art, through the analysis of the materials of welded structural members and the welding stress distribution, the present invention can quickly plan the composite peening area and peening path of welded structural members by combining the peening-induced stress method, quickly design the composite peening process of welded structural members, and save the design process and processing time.

[0023] 3. The invention simultaneously combines sandblasting technology to correct the surface quality of the strengthened welded structural member, can quickly complete the strengthening processing of the welded structural member, improve the surface quality of the welded structural member at the same time, and control the forming error of the stress distribution and the roughness error, etc. within a certain range. Brief Description of the Drawings

[0024] Figure 1 It is the flowchart of the method provided by the embodiment of the present invention;

[0025] Figure 2 It is the schematic diagram of the division of the shot peening area of the panel;

[0026] Figure 3 It is the schematic diagram of compound shot peening strengthening; Specific implementation manners

[0027] According to the characteristics of the aviation welded structural parts and the requirements of processing strengthening, analyze the distribution characteristics of the welding stress of the structural parts. According to the shot peening induced stress method, divide the laser shot peening and numerically controlled shot peening areas and shot peening paths of the strengthening surface of the structural parts. Stick protective tapes on the laser shot peening areas of the structural parts, and clamp the structural parts to be strengthened on a special fixture.

[0028] And move the special fixture to the numerically controlled shot peening processing space position, start the numerically controlled shot peening machine tool, move the shot peening head to the area to be processed, and the shot peening path is from the weld edge to the area with small welding stress and no welding stress. After completing one numerically controlled shot peening area, adjust the fixture and continue to complete the surface of the subsequent mechanically shot peened structural parts to be processed. After the numerically controlled shot peening strengthening processing is completed, remove the protective tape on the surface of the structural parts, clean the surface of the structural parts, and apply black paint on the surface of the laser shot peening strengthening area as the absorption layer for laser processing. Move the special fixture to the laser shot peening system processing area, adjust the special fixture to make the surface to be processed perpendicular to the laser beam, and provide water flow (as the constraint layer) to the black paint surface of the structural parts through a water pipe. The laser spot path is from the middle of the weld to the surface of the weld edge. After strengthening one weld, adjust the fixture and continue to strengthen the remaining divided laser shot peening areas. After the laser shot peening forming processing is completed, dry the panel, remove the black paint on the surface, detect the surface and strengthening quality of the structural parts, correct the surface of the structural parts by sandblasting, and perform shot peening on the laser shot peening and numerically controlled shot peening junction area to improve the surface quality of the panel. Detect the forming quality of the panel, and deliver it after the surface production residual stress distribution error is less than ±10 MPa and the surface roughness error is less than ±0.5 μm.

[0029] Embodiment 1:

[0030] According to the compound shot peening strengthening processing method for aviation welded structural parts, it mainly includes the following steps:

[0031] Adjust the professional fixture, and conduct material and welding stress distribution analysis on a 6061-T6 aluminum alloy welded structure with dimensions of 500mm * 300mm * 3mm and a weld length of 100mm. Divide the laser peening area and the CNC peening area. Considering that the welding stress at the weld is significantly higher than that far from the weld, set the area with welding stress greater than +10MPa as the laser peening area. Stick protective tape on the laser peening area for protection, clamp the welded structure on the professional fixture. The CNC peening process uses S230 shot, with a coverage rate of 100%, and the peening intensity is 0.36mmA. Move the fixture to the processing area of the CNC peening machine tool, and conduct CNC peening strengthening processing on the welded structure. After mechanical peening is completed, remove the protective tape on the surface of the structure, clean the surface of the structure, and perform black paint coating on the laser peening area. Clamp the structure on the professional fixture and move it to the laser peening working area. The output energy of the laser peening is 6J, and the laser spot diameter is set to The laser pulse is 23ns, and the overlap rate is 50%. The laser peening system conducts laser peening strengthening operations on the welded structure according to the pre-designed process parameters and paths. After peening and strengthening one weld, adjust the professional fixture and continue to peen and strengthen the subsequent areas to be processed. After the laser peening operation is completed, remove the black paint on the surface and conduct drying treatment. Detect the surface of the structure, and treat the surface of the structure with sandblasting. After composite peening strengthening, the surface production residual stress distribution error is less than ±10MPa, and the surface roughness error is less than ±0.5μm before delivery.

Claims

1. A composite shot peening strengthening processing method for an aviation welded structural part, characterized in that, The aviation welded structural part includes at least 1 weld seam on the surface of the structural part. The composite shot peening strengthening of the aviation welded structural part includes the following steps: Step 1: Analyze parameters such as the stress distribution of the weld seam of the structural part and the material of the structural part according to the structure of the aviation welded structural part. Step 2: Determine the strengthening processing task of the aviation welded structural part according to the parameter analysis. Design the process parameters of the composite shot peening on the surface of the aviation welded structural part by the welding stress distribution of the structural part and according to the structure and material characteristics of the structural part. Step 3: Clamp the aviation welded structural part to be strengthened in the working area of the numerical control shot peening machine tool by a special fixture, and perform numerical control shot peening strengthening processing on the positions with lower stress distribution and the stress-free surface of the structural part by numerical control shot peening. Step 4: After the numerical control shot peening strengthening processing is completed, clamp the aviation welded structural part in the processing area of the laser shock peening system by a professional fixture. The laser shock peening system performs shot peening strengthening processing on the places with larger welding stress distribution such as the weld area by a high-energy laser beam. Step 5: After completing the numerical control shot peening and laser shock peening strengthening, check the surface quality of the strengthened structural part, perform shape correction on the surface of the structural part by a sandblasting device, and deliver it after checking that the surface quality (roughness, profile, etc.) meets the requirements.

2. The composite shot peening strengthening processing method for an aviation welded structural part as described in claim 1, wherein In Step 1, it is also necessary to determine the division of the surface strengthening area of the structural part, the mechanical shot peening area and the laser shock peening area according to the welding process parameters and material characteristics of the welded structural part. The welding process parameters and material characteristics include the analysis of the welding stress distribution and the material characteristics of the structural part.

3. A composite shot peening strengthening processing method for an aviation welded structural part as described in claim 1, characterized in that, In Step 2, divide the numerical control shot peening and laser areas according to the surface stress distribution and the target strengthening requirements of the welded structural part, and design the process parameters of the numerical control shot peening and laser shock peening according to the shot peening induced stress method. The coverage rate of the numerical control shot peening is 20%-50%, and the overlap rate of the laser shock peening is 50%-80%.

4. A composite shot peening strengthening processing method for an aviation welded structural part as described in claim 1, characterized in that, In Step 3, the panel can be clamped in different areas according to the designed shot peening process information by a special fixture to ensure the numerical control shot peening and laser shock peening forming processing. At the same time, according to the forming processing process, adjust the position of the panel to be processed by the fixture to achieve more flexible clamping and processing.

5. A composite shot peening strengthening processing method for an aviation welded structural part as described in claim 1, characterized in that, In Step 3, before the mechanical shot peening strengthening, it is necessary to perform protective treatment on the welded structural part, paste protective tape on the areas that need laser shock peening strengthening, which can protect the areas to be laser processed during the numerical control mechanical shot peening process; after the mechanical shot peening strengthening is completed, clean the surface of the structural part, remove the protective tape in the laser processing area, and apply black paint as the absorption layer in the laser processing.

6. A composite shot peening strengthening processing method for an aviation welded structural part as described in claim 1, characterized in that, In Step 5, after the laser shock peening and numerical control shot peening forming are completed, remove the surface protection tape and black tape, perform sandblasting treatment on the connection area of the two shot peening forming to reduce the surface difference between the two areas, and treat the out-of-tolerance parts on the surface of the structural part. The sandblasting is carried out from the mechanical shot peening area to the laser shock peening area for surface treatment.

7. A composite shot peening strengthening processing method for an aviation welded structural part as described in claim 3, characterized in that, During the laser shock peening strengthening process, the shot peening starts from the middle position of the weld seam; during the numerical control shot peening strengthening processing, the shot peening is carried out from the edge of the weld seam to the edge direction of the surface of the structural part.

8. A composite shot peening strengthening processing method for an aviation welded structural part as described in claim 3, characterized in that, Welding stress distribution of aviation welded structural parts σ(y): Longitudinal stress at a distance y from the weld center line, σ max : Maximum tensile stress at the weld center (usually close to the material yield strength σ y ), w: Half-width of the heat-affected zone (HAZ); σ y (x): Transverse stress at a distance x from the weld end, σ trans : Peak value of transverse stress, L: Stress attenuation characteristic length. In shot peening, through the composite shot peening method for aviation welded structural parts, after the composite shot peening of aviation welded structural parts, the residual stress distribution error on the surface of the welded components can be made less than ±10 MPa and the surface roughness error less than ±0.5 μm through the composite shot peening.

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