Study On Non-sinusoid Oscillation Control Used In Continuous Casting Mould

This doctoral dissertation focuses on the mold of a small square billet continuous casting machine as a controlling object, an oscillation mechanical model for a continuous casting mold is a four connecting rod and a half plank springs device is built at laboratory used for research work. The closed ioop servo system controlled by a servovalve, in which the displacement and pressure sensor is used as feedback element, has been developed. The mathematical model of hydraulic servo system is also built includes the nonlinear flow in the orifice, current saturation of the servo valve, output pressure saturation, volume change of the cylinder chambers and the friction load. At first, the methods that construct non-sinusoidal oscillation waveform curves are given. The waveform curves and waveform curve parameters are built into an accurately analytic formula. The synchronization control model of drawing speed and oscillation parameters is established at the same time. In order to make further improvement on precise control quality, a digital control and analog mixing system composed of HY-6050 photoelectricity separate fl/A and HY-6040 A/fl cards and microcomputer carrying out control algorithm is used. A switch can change the digital control and analog control systems and independence works in separately. The microcomputer is an IPC-6l00/586/l66MiHz PC that is applicable in industry. Because developing a real time inspecting program, work efficiency is advanced and the operation is simplified by using menu + icons on the computer. Some software, such as data acquisition and process, waveform generation, parameter design and modem control arithmetic, are also developed. The system integrates control, measurement and analysis. So it has a higher performance to price ratio. In this article, the design methods for controlling strategy in an oscillation control for continuous casting mold are discussed in detail. The control strategy on model reference adaptive control and VCS control is given. Taking account of the indeterminate and the presence of large friction load and the changing parameters of the system, a ~ control design technique is found to optimize mixed S/T sensitive strategy. This is the first time that the ~ control theory is applied to (in continuous casting) control the mold oscillation. The digital simulation results show that the close-loop response with H~, controller performs better and makes the closed-loop system robust. By using weighting functions to compensate the input and output signal, the transfer function of the closed loop system can be loopshaped. The He,, controller that is studied not only can be used in the system, an accurate model of which is difficult to obtain but also can be used in the system that has friction load and non-linearity. So this controlling algorithm is valuable for engineenng. Furthermore, this dissertation presents a novel dynamic model on the friction and a compensatory scheme that is based on this model can be used in the oscillation system for the continuous casting mold. The process is molded by a first梠rder nonlinear differential equation. The parameters of the dynamic friction model are obtained by using off line estimation techniques. The model is also used to construct a friction observer and to perform friction compensation. Both frequency domain and time domain simulation results show that the control high level accuracy can be achieved. industry experiment is successful and molten steel continuous casting is accomplished. The drawing split and leak accident which is caused by the coherence...