Forming Analysis And Processing Of Complex Thin-walled Surface Aircraft Sheet Metal Parts


Sheet metal parts are an important part of modern aircraft. Relevant surveys and statistics show that sheet metal parts account for 70% of the total number of aircraft parts. From the perspective of production workload, the labor amount is about 15%. The complex structure, rich volume variety and large external expansion size are all significant features of sheet metal parts, and their processing quality will have a direct impact on the overall production progress and quality. In order to effectively meet the production needs of modern aviation enterprises, it is necessary to realize the utilization of advanced mechanical automation technology in combination with the actual situation.

 

1. Parts Analysis

 

We analyze the aluminum alloy material with a thickness of 0.3mm. After scientific thinking and analysis, we summarize the main problems in the following points and analyze them carefully.

 

(1) The thickness is thin, which has a direct impact on its ductility, resulting in the problem of poor ductility.

 

(2) One-time corner forming cannot be realized in a true sense, and phenomena such as cracking and wrinkling are generated in this process.

 

(3) There is an inseparable and close relationship between the surface processing position and the mold design work, but it is difficult to design and carry out the mold design work, which greatly hinders the smooth progress of the parts processing work.

 

(4) The complexity of parts is a significant feature of 3D surface design, so continuous process experiments are required, which will lead to an increase in cycle and cost to a certain extent, which is not conducive to the realization of the maximum economic benefits for relevant enterprises.

 

(5) The ultra-thin welding processing method used in the actual processing of the parts, so there will be great difficulties in welding the three-dimensional curved surface. This will increase the workload to a certain extent and have a negative impact on the improvement of construction work efficiency.

 

2. Discussion on the Feasibility of Part Forming

 

(1) The effective establishment of the model can be achieved by using 3D design software. In this process, attention should be paid to the use of parameterized commands. In order to promote another plane to be produced under the part in a true sense, it is not allowed to use scientific means to achieve the correct model. The establishment of 3D model coordinates. Take care to keep its height at a distance of 1mm from the ground. When actually setting the corresponding position, pay attention to the organic combination with the aviation sheet metal design module in the software.

 

(2) Pay attention to the reasonable use of CATIA software when actually analyzing the thickness. On this basis, not only the material thickness can be selected, but also the setting of the material properties of the part can be completed in this process, which will lay a solid foundation for the subsequent part forming work. Solid foundation. In the integral forming of the part, the thickness will change greatly, and the change rate at the bending corner will show the largest trend, which can explain that the wrinkling problem will occur at the corner to a certain extent.

 

(3) The stress distribution of the formability can be performed in the CATIA software. Through the stress distribution graph, it can be obtained that the part has relatively large stress change characteristics, and the stress distribution of the part is 158.3MPa~427.5MPa. Among them, the stress change is in the fold. It is the largest outside the corner and can reach a maximum of 427.5MPa. This very variable corner point can be seen, the bend corner is vulnerable to damage.

 

(4) The application of CATIA software can also realize the strain analysis of the part. From the analysis of the results, it can be seen that the strain of the part has a relatively large change, and the strain changes from 0.0168 to 0.2345. Likewise, the largest strain occurs at the corners, which is prone to some wrinkling and cracking.

 

(5) Using CATIA software to further expand and analyze parts, it can be seen that the expanded graphics have a lot of intersections. Through CAE software, the content that cannot be displayed on the plane can be realized, so that the design defects can be minimized.

 

3. Parts splitting and unfolding

 

(1) In forming, the use of CATIA software can ensure further analysis of formability. Combined with the specific situation, it can be divided into two parts to be processed, mainly including surface forming and plane forming. With effective splitting, complex parts can be divided into two parts. The problem is simplified, and the problems of cracking and wrinkling are avoided as much as possible;

 

(2) Analyze the forming of the part through CATIA software, and carry out the analysis and design of the relevant forming plane and curved surface for the relevant stress, strain change and thickness in the part;

 

(3) After the sheet metal parts are unfolded and designed, in order to further process, it should be ensured that the effective unfolding process is carried out to ensure that the shape and size of the sheet metal are determined. Combined with the traditional unfolding method of sheet metal parts, due to the manual development based on experience, there are mainly the following difficulties: First, the problem of relatively low efficiency, it is easy to make mistakes in the unfolding, and further trial and error should be carried out; the second is the large workload , the specific process is very cumbersome; the third is the problem of relatively low precision, due to the large proportion of relying on experience, resulting in unnecessary waste of materials and labor. Make full use of the automatic unfolding of the sheet metal module in the computer-aided design software CATIA, can use the computer to process the automatic unfolding process, realize one-dimensional processing, and use the automatic calculation to obtain the unfolded shape, which can have the advantages of high precision and zero error rate.

 

(4) Based on the analysis of the formability of the parts, a certain comparison is made. From the split forming and the integral forming, it can be seen that for the integrally formed parts, the corresponding stress and thickness requirements cannot meet the material mechanics. performance, there will be surface intersections.

 

4, mold rapid design

 

Using the module modeling instructions in the 3D design software CATIA can ensure the establishment of a 3D model suitable for practical applications, and at the same time, establish 3D coordinates, and use the extraction volume command to effectively extract parts from the inner surface and inner plane, so that the 3D model can be hidden. Through the surface sweep, the related processed surface can be obtained, ensuring that it and the extracted body can be effectively stitched and processed as a whole. The plane is then established in the part, kept horizontal, stretched, effectively trimmed into a die, and positioned. On the basis of stretching, the trim body command should be used for effective trimming, which requires the shearing process between the target body and the cutter body, and the punch forming shape should be generated according to the actual situation. Then, the difference operation in the stretching command should be used. , effectively get the punch mold. Similarly, according to the three-dimensional software, the corresponding upper mold and female mold can also be obtained.

 

5, manual forming steps

 

Manually, on the basis of the above, it is possible to form punches and concave dies to form planes and curved surfaces of related parts, effectively ensuring that the corresponding planes, curves and 3D modeling are highly consistent. The relevant coordinate detection, which can measure the corresponding plane and curved surface, meets the requirements of the pattern.

 

6. Parts Welding Treatment

 

For the welding process of aluminum alloy, due to the existence of hot cracks, there are mainly cracks, and the related cooling heat affected zone metal will appear embrittlement, cracks, stress cracking, intergranular corrosion and other problems. Similarly, For the processing of this material, problems such as relatively poor thermal conductivity, relatively large welding deformation and relatively large linear expansion coefficient are inevitable.

 

7. Conclusion

 

Using the manufacturing technology in the 3D-aided design software, the integrated process from design to manufacturing of complex thin-walled surface sheet metal parts in aviation can be realized. Through intelligent manufacturing methods, it can effectively ensure that the product development time is greatly shortened, and the research and development cost is effectively reduced. cost, and help to reduce the error rework rate.

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