| As one of the key components of the traveling wave tube(TWT) system, the helical slow wave structure(HSW) plays an important role in the field of civil and national defense. In the assembly of HSW, there is a usual phenomenon, that is, the accuracy stability is not good even with qualified parts, resulting in low assembly yield. Therefore, system performance cannot meet the design requirements. The main cause of this phenomenon is the deficiency of effective and quantitative method to analyze the relationship between manufacturing features of parts and system accuracy stability, which is influenced by the stress state of the parts after assembly in a large extent. In consequence, to lay the theoretical foundation for the performance prediction, simulation analysis and assembly precision control of the traveling wave tube, and to provides the method and basis for the design, processing and to assembly process optimization of precision mechanical system, this thesis investigated the relationship between the manufacturing features and the stress state of parts, while taking a helical slow wave structure as example.The first part introduces the background of the research, which is about assembly performance of helical slow-wave structure with manufacturing characteristics, then generation and development of TWT, assembly performance, and then elaborates on the source of the problem, the purpose and significance of the research, major contents of the research, the present research status at home and abroad, and major research methods. Based on analyzing the existing research works and literatures of helical slow-wave structure, aimed at the existing problems of stability and accuracy of system, some crucial technology are theoretically and experimentally studied in this dissertation.1. Detection of key components. The surface shape accuracy of parts is detected by using two-dimensional detection platform of CMOS. And the data of surface shape accuracy is processed.2. Theoretical research on model method of modeling with shape error based on reverse engineering technology. Through the research of 3D solid modeling method with manufacturing characteristics, objective to lay a theoretical foundation for simulated practical processing parts and study on assembly performance.3. 3D solid modeling with manufacturing characteristics. Combined with the component parts size and material characteristics, based on data processing of MATLAB and finite element simulation modeling method of Pro/E reverse engineering, high-precision 3D model, which accurately describe the part surface shape error, is established.4. Study on the nonlinear assembly performance of HSW. The contact surface of the complexes should be theoretical analysis of the influence and the simplified for ideal ring model, we calculated the radial compression and shear force of the spiral spring. Different length parts of HSW, different parts of HSW with shape error, different parts of HSW with shape error and size error are assembly simulation. At the same time to solve the three problems of finite element simulation, which are nonlinear contact, nonlinear sliding, and large deformation of thin wal, processing parts are simulated. Theoretical basis of analysis on assembly property and assembly technological optimization are established.5. Study on thermodynamic assembly performance of HSW. The change of temperature field can cause the deformation of the mechanical structure of HSW, so the assembly accuracy of HSW is not predictable. On the other hand, the change of temperature field can also lead to the thermal stress of the mechanical structure, which influence on precision stability of HSW. On the basis of the basic theory of heat conduction and thermal deformation, thermal stress state and thermal deformation of HSW, in the case of different shape error, size error and temperature field, are studied by thermal-structural finite element method. It lays the foundation for the research of heat treatment technology... |
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