Control Strategy Study On The Hydraulic Non-Sinusoidal Oscillation For Continuous Casting Mold

Continuous casting mold oscillation system is a key link to improve the quality of continuous casting billet, most of which take the form of mechanical sinusoidal oscillation technology at present. With the improvement of billet quality requirements and the needs of high-speed continuous casting, mechanical sinusoidal oscillation technology has been unable to meet the requirements of the modern continuous casting, while the electro-hydraulic servo-type non-sinusoidal oscillation reduce the negative strip time while frequency unchanged, which can effectively improve the lubrication between the billet and the mold wall, reduce friction and the accident rate of pull leakage, improve billet quality, so the electro-hydraulic servo-type non-sinusoidal oscillation has become a hot spot of continuous casting mold oscillation technology development.Considering the features of mold oscillation system, the non-sinusoidal waveform's mathematical expressions of displacement and speed were given in this paper, and the parameters were analyzed. According to the principle of electro-hydraulic servo control systems and the characteristics of mold hydraulic servo system, the transfer function of valve-controlled asymmetric hydraulic cylinder was derived; considering the natural frequency of valve-controlled hydraulic cylinder, the mathematical model of the servo valve was established, and the stability of the servo system was analyzed through the MATLAB system.There is uncertainty in modeling of mold's non-sinusoidal oscillation system, and the parameters of system change greatly, at the same time, the traditional PID control method is model-based control, so it is difficult to adapt to the typical time-varying systems in a larger context. The adaptive PID is a control method essentially does not depend on the model, comparatively apply to those control objects which possess uncertainty or a high nonlinearity, and has strong adaptive and learning capabilities. Therefore, the development of adaptive control system has great guiding and practical significance for the mold's non-sinusoidal oscillation control system. The conventional PID controller, fuzzy adaptive PID controller and three kinds of single neuron adaptive PID controller were designed to apply to mold's non-sinusoidal oscillation control systems in this paper. The results of simulation and experiment show that the single neuron adaptive PID controller improved the response speed of the mold oscillation and effectively ensured the control target--negative strip time of mold oscillation; reduced the distortion of the tracking waveform, which will make the mold oscillate according to a given characteristic curve of non-sinusoidal oscillation. What's more, the running time of the program on PLC is also within reasonable limits, which ensured the real-time control.