Due to the centralized process and automatic tool change, the machining center reduces the time of workpiece clamping, measurement and machine adjustment, so that the cutting time of the machine tool reaches about 80% of the starting time of the machine tool (only 15-20% for ordinary machine tools); at the same time, it also reduces the time of workpiece turnover, handling and storage between processes, shortens the production cycle, and has obvious economic effect. Machining center is suitable for small and medium batch production with complex shape, high precision and frequent product replacement. Now, manufacturing large-scale aircraft in China is one of the important development directions of China’s aviation industry in the future. The development of large-scale aircraft needs high support, elegant and sharp related technology. The very large wall part refers to the whole wall part which is widely used in large aircraft with large scale (20m) length direction. This part has the characteristics of large size, complex structure and high precision, which makes it difficult to manufacture large aircraft structure.
Very large parts of the wall have different loopholes to strengthen the overall structure, such as the rod due to high dimensional accuracy requirements, most of the production CNC processing means to complete. The development of China’s domestic large aircraft is used for the structural parts of large wall. The accuracy requirements are as follows: the thickness tolerance of network and rod is + / – 0.15mm, the height tolerance of rod is + / – 0.2mm, the outer wall surface is flat, and the distortion is not more than 5mm, which cannot be encouraged. It is necessary to have scientific and reasonable processing deformation control technology to meet the processing requirements.
Research on deformation control technology of super large wall parts processing, the whole deformation control technology, the whole verification in the actual processing deformation control technology, can effectively control the deformation of super large wall parts, the general processing accuracy is 0.2mm, has achieved good results, has important engineering application value.
Deformation control process of integral machining
The whole process of the super large wall part is analyzed, and the whole size blank large tensile aluminum alloy plate is formed. Finally, the asymmetric integral wall part with “one side smooth, one side” structure is formed. Generally, the material removal rate reaches 95%. In the process of creating pre stretched aluminum alloy plate, the machining deformation is mainly caused by the release of residual stress, especially for large-size parts. In the process of machining removal rate, if the residual stress release of this problem can not be well solved, it is easy to lead to the machining and treatment process of large deformation parts, resulting in the size out of tolerance scrap or the product does not meet the requirements.
Combined with the machining process of the very large wall part, the following deformation is set to control the whole process. The process includes: large edge cavity, positioning, surface finishing, roughing, seasoning, vacuum clamp, online measurement and completion, etc. The main purpose of the process of releasing residual stress in a large margin groove cavity is not to form the characteristic size. It is the key to control the deformation process by quickly deleting a large number of residual stress releasing blanks in surplus materials; positioning surface finishing, rough machining and natural aging rough machining release residual stress, and further release residual stress, Processing process has formed a unified allowance part blank, and the role of natural aging, easier to control processing deformation. During the preparation of vacuum clamp and on-line measurement allowance process, vacuum clamp is a way to ensure the stability of clamping part. Through the change of on-line measurement, through rough machining and natural aging allowance, the processing technology can be adjusted to ensure the accuracy of feature size. After finishing the finishing process, the wall plate can be treated,
In the above processes, each process considers releasing pressure and unified pressure to control the part of machining deformation. No matter in the process of form feature size rough machining or dimension precision machining, the analysis and consideration of parts machining is an important part of deformation control, so as to realize the overall control of machining deformation, Controlling the influence of machining deformation is to ensure the machining accuracy of parts.
In the process of precision parts processing, because of its complex structure and special materials, there will be a variety of stress and deformation problems that can not be predicted by engineers in the process of processing