With the increasingly fierce competition in the aviation field, higher requirements are placed on aircraft performance. The characteristics of modern aircraft structure design are light weight, high structural strength, and reduced aircraft's own structural weight, which means improved aircraft mobility, enhanced carrying capacity, and longer flight distances; As the weight is reduced and the structural strength is increased, the service life of the aircraft can be extended. For this reason, in the design and manufacture of aircraft structures, some large and complex structural parts, especially the main bearing structural parts (such as aircraft girders, bulkheads, siding, etc.) generally adopt an integrated structural design. The overall structure can not only reduce the number of parts, reduce the weight of the structure, but also increase the structural efficiency and reliability of the aircraft by a factor of ten or even ten. It can be said that the application of the integral structural parts on modern aircraft is a major advancement in manufacturing technology. However, in the NC machining process of the integral structural parts, the bending, twisting and bending and torsion combination are often deformed due to the initial stress of the blank, the asymmetry of the structure and the incomplete improvement of the processing technology; It will cause instability, which seriously affects the production efficiency of the overall structural parts of the aviation and the accuracy of the final product.
At the same time, with the development of materials science and manufacturing technology, many new difficult-to-machine materials, such as titanium alloys, nickel-based alloys and super-alloys, are widely used in aerospace structural parts. These materials have high strength and hardness. Good plasticity and toughness, poor thermal conductivity, microscopic hard spots, and active chemical properties. The cutting force and cutting heat of the tool are obviously increased during the cutting process, which leads to serious processing contradiction and makes it typical. The difficult processing materials seriously restrict the improvement of processing efficiency and product quality. The processing precision and processing efficiency of the aviation integrated structural parts are the bottlenecks restricting the progress of the existing advanced models and the development of new models. Especially the research and development of large aircraft makes this key process problem particularly prominent.
The processing and manufacturing of aviation integral structural parts is a systematic project. Machine tools, tools, clamping and crafts are all key technical links in this system. Any one of these links will affect the quality of the product. Based on the analysis of the current research status, existing problems and development trends of each key processing technology, this paper proposes corresponding solutions and feasible technical methods to achieve the efficiency of the overall aviation structural components. High-precision machining provides a theoretical basis.
Large structural parts processing requirements for machine tool functions
In the processing of difficult-to-machine materials such as aviation titanium alloys, the cutting force is high, the cutting temperature is high, and vibration is easy to occur. Therefore, in the processing and manufacturing of aerospace structural parts, the machine tool is required to have high rigidity, high power and high torque characteristics, and has better performance. Anti-vibration ability. The spindle of the machine tool directly supports the movement of the workpiece or the tool during the machining process. The performance of the spindle has an important influence on the machining quality of the workpiece and the production efficiency of the machine tool. Increasing the rigidity of the spindle will be one of the important links to ensure the accuracy of the overall structural components of the aircraft. . The coupling parts of the guide rails and support members of the machine tool have a great influence on the machining quality of the workpiece and the machining characteristics of the machine tool. The coupling parts are often the weakest part of the local stiffness, and the coupling method has a great influence on the stiffness. If the size of the guide rail is wide The double wall connection type is applied. When the guide rail is narrow, a single wall or a thick single wall joint may be used, or a vertical rib may be added on the single wall to improve the local rigidity.
At present, the design and development of machine tools with high stiffness, high power and high torque characteristics mainly adopt optimized design methods and finite element simulation analysis methods.
Optimization design is the transplantation and application of optimization theory in the field of mechanical design. The basic idea is to establish a mathematical model that reflects engineering design problems and meets mathematical programming requirements based on the theory, methods and standard specifications of mechanical design, and then uses mathematical programming methods and Computer computing technology automatically finds the optimal solution for design problems.
The finite element method based on physics simulation is an effective means to study the dynamic characteristics of the system structure in recent years. Through the finite element analysis of the dynamic process of machine tool processing, the bearing performance of the machine tool and the load and stress changes of the spindle part can be observed in advance, so that the limited use can be utilized. The meta-analysis results optimize the dynamic characteristics of the machine tool.
In the finite element analysis, the “bonding†method can be used to simulate the fixed relationship between the machine parts. The contact between the moving platform and the baffle is sliding contact and is lubricated with oil. The sliding friction coefficient is relatively small. The approximation is considered to be frictionless sliding, and the "frictionless contact" method can be used in the analysis to simulate this connection. For the bearing condition of the spindle, the real spindle, tool and workpiece can be constructed by applying boundary conditions such as displacement and speed to the spindle, tool and workpiece. Through the finite element simulation analysis of the dynamic characteristics of different parts of the machine tool, the system structure of the machine tool is optimized, and finally the machine tool system capable of efficiently processing the whole aviation structural part is developed.
As the application of many new aerospace materials and the geometry and structure of aerospace structural components continue to improve and renew, the machine characteristics of such parts are required to be higher. In addition to the characteristics of stiffness, power and torque, mechanical machinery for the machine tool is required. Partially, the cooling system, the working space and the linkage of the machine tool are further designed to develop a CNC machine tool suitable for the structural characteristics and material characteristics of the overall structural part of the aviation to achieve efficient and high-precision machining of the overall structural components of the aviation.
Jiangsu Dingtian Stainless Steel Products Co., Ltd. , https://www.dingtiancasting.com