System Modeling And Dynamic Performance Analysis For Huge Die-forging Press Under Extremely Low Speed

Modern aviation and aerospace fields are developing to extreme directions, such as high-reliability, long service life and lightweight. High-precision die forging with large-scale integral structure is the effect method and technical way to achieve this goal. Huge forging press is the key equipment to guarantee the quality of these forgings. It has become the representation of basic manufacturing ability and the top priority of equipment manufacturing industry, so it plays an irreplaceable role in the major strategic projects and modernization of national defense.These high-precision die forgings always need huge forging press has the ability to steady movement under extremely low speed. But large inertia forging press is an electro-hydraulic coupling system with multi-cylinder parallel-driven. There exists the influence of many uncertain factors under extremely low speed, such as nonlinear friction, this cause the press is difficult to obtain required dynamic performance. Therefore, this paper studied on extremely low speed system modeling, dynamic performance analysis and extremely low speed movement control, the main research work is as follow:(1) Large inertia equipment system modeling and parameter identification under extremely low speed. Based on force analysis to the moving beam of forging press, considering the impact of low-speed nonlinear friction, establishes the mathematical model of large inertia low-speed system; for nonlinear dynamic mathematical model contains unknown parameters, based on the experiment on4000T isothermal forging press, proposes a parameter identification method based on PSO, obtains the model which can true reflect huge forging press’s low-speed movement, and it’s accuracy is verified through experiment.(2) Large inertia equipment’s dynamic performance analysis under low speed. According to linear system theory, comprehensively analyses the impact of system parameters to press’s low-speed performance, such as system stability, response delay and transient response quality. Through simulation conducted on4000T forging press, reveals the influence law of nonlinear friction to large inertia equipment under extremely low speed, such as the negative damping characteristic of friction is the main reason lead to low-speed system’s instability.(3) Huge forging equipment’s control research under low speed. For huge forging press exists the influence of nonlinear friction and uncertainty under low speed, designes the friction compensation controller, and then proposes a compound control method combined friction feed forward compensation control and feedback control based on PID. Simulation proofs this method can effectively deal with nonlinear and uncertainty, guarantee the system’s stability and robustness, achieve the press’s low-speed steady movement. Compared with PID control, the result shows that this method has better control performance.