| ABSTRACT:Modern aviation and aerospace are developing toward high reliability, long service life, light weight and other extreme direction, the large complex integral components with high accuracy is an effective means to achieve this goal. And the isothermal forging manufacturing technology of high performance complex pieces requires the large inertia forging equipment must be stable operation in extremely low speed, but the stable operation in low-speed of large inertia equipment is hardly acquired because of the complex multi-cylinder hydraulic drive system, time-varying forging deformation resistance and nonlinear friction. So, the simulation modeling of large inertia forging equipment, low-speed performance analysis and control method were researched in this paper, the main research contents are following:1) The combining model with forging equipment operation process and material rheoforming process is built. The link between equipment operation and material forming process in traditional modeling methods is split; it can not analyze the impact of system parameters at specific molding process to forging performance, but also can not cope with the influence of process parameters on material forming press systems, which lead to the low-speed performance can not be assured. Therefore, the combining model with forging equipment moving process and material rheoforming process was built, and the relationship between material rheological parameters and low speed driving performance in forging equipment is reflected. All of these provide the research basis for low-speed moving performance analysis.2) The influence rules of large forging presses running in low speed are analyzed. Firstly, the dynamic model of moving process was derived and analyzed, and the relation between friction and low-speed operation was derived, the influence rules about difference between static and dynamic friction and friction critical speed on low-speed crawling were acquired. Secondly, these rules were tested on combining simulation model, and the parameter region lead to low-speed crawling was obtained. Lastly, the relationship between Micro-rheological forming parameters and low-speed performance was analyzed.3) The forging equipment works with nonlinear deformation resistance, friction, and unknown disturb, considering of the stable operation problems, the joint control method with inner and outer layers was proposed:the inner layer is PID controller which can control the system coarsely, and the velocity fluctuation can be reduced; outer layer is model predictive control based on subspace, which can improve the accuracy. The result shows that the steady operation of the large forging equipment on extremely low speed can be acquired by the new control method, and the result is better than the traditional control method.4) The operation velocity of forging equipment can be changed when load change suddenly, velocity switch or on external interference, in view of this problem, the adaptive control method with online modeling and integrated controller was proposed. For characteristics of time-varying system, the weighted control method with two controllers is used, both controllers are model predictive controller with high control accuracy and fuzzy PID controller with robustness, the online models are acquired by subspace identification and clustering identification. The simulation result shows that system can adjust quickly when the load changes suddenly, the control output has a good following and stability performance, and this control method is better than others. Full total figures54, tables16, references84... |
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