Modeling And Operating Performance Analysis For Complex Forging System

Abstract:The development of aerospace technology depends on large-scale high-performance overall die forgings. This kind of forgings’ precision forming requires the forging equipment must have a ability to operate stably.But, large forging press is a complex electro-hydraulic coupled system.Because of the oil pulse, nonlinear friction and strong nonlinear load, its speed is extremely prone to shock and even creep in the forging process.So,this paper did a research on molding,operation performance analysis and stable control for forging equipment. The main contents are as follows:1) To derive the approximate speed model of the large forging press. Firstly, the press’motion model was established by considering the nonlinear load,friction and nonlinear hydraulic system. Because this model has a strong nonlinear characteristic. It cannot be directly solved analytically. The numerical solution also can hardly got the universal rules.So, a proximate method to solve the speed was proposed. By mathematic exchange, a standard vibration equation was obtained. Based on this, with the help of nonlinear force vibration theory, the system’s approximate speed was derived. The experiment showed the approximate speed had a good approximation accuracy. All of these provided a foundation for the analysis of press’s dynamic performance.2) To obtain the press’performance.The approximate speed model includes a parament described by a complex differential equation.lt brings up a big problem for analysis the press’performance under the low speed. So,by analysis the speed model, a condition that speed can be solved analytically was firstly founded. And then, the stable run condition, speed shock condition, creep condition were obtained under this condition.However, to the work condition which did not satisfied speed analytical solution, a convergence and balance point of speed equation were analyzed.At last, the speed shock condition and creep condition were also founded under this condition. Simulations and experiments all vertified the validity of these laws.All of these provided a theoretical basis for controling the equipment stable operation. 3) To design a forging process’ control strategy. Because of forging system’s complex operating rules and the time-varying characteristic during the whole forging process, a multi-model control strategy was came up with. This strategy first divided the whole forging process into many sub-forging workspace. By the experimental data,the corresponding sub-models were established. According to the characteristics of sub-models, the corresponding sub-controllers were then also designed.At last, a gaussian weighting device was then proposed to coordinating the sub-controllers,to deal with the coupling between the sub-models, and further to achieve a smooth precise control of the press’ full stroke ultimately.