| Parallel multi-roller straightener is an important equipment in the materials straightening industry. But high-precision straightener with hydraulic position servo-control can hardly be made in china. The most pivotal key of straightener is position control precision, which directly affects products' quality. This research focuses on the position control system and implementing the actual control process with PLC on the basis of theory analysis.The expression of upper rollers' press amount that is the key parameter in straightening process is acquired by means of researching on the theory of parallel multi-roller straightener. The mathematical model is deduced according to the hydraulic control system theory, and the simulation is made by MATLAB. A SIEMENS PLC is used to control the straightener and acquire data that are used to compare with simulation.Chapter one is concerned with the background, significance and primary contents of the research. At first, the background is introduced, including the technical actuality of material straightening industry and roller straightener in the world, and the trend of disk saw process. Then the actuality and development of modern electro-hydraulic servo-control are also summarized. At last, the main research contents are presented.The work theory of parallel multi-roll straightener is first introduced in chapter two, and the key parameter's mathematical expression is acquired and simplified according to engineering application. Then mechanical composing, control system composing (hydraulic and electric control system), work theory and control destination are presented.In chapter three, the mathematical model is acquired according to the basic equations of electro-hydraulic servo-system and the linear model is established at stable operation. The transfer function and control diagram are obtained by L transform. Last, some parameters concerning control system are computed.In chapter four, computer simulation with common PID control strategy is made in SIMULINK of MATLAB on the basis of mathematical model. And the synchronous control methods are also discussed.Chapter five is concentrated on PLC software program of control system, including flow chart, interface design about the touch panel and some program details. Then operation on the spot and data acquisition that is used to compare with simulation are discussed.In chapter six, some conclusions concerning some existing problems and future work about hydraulic straighterner's control system are made, which are the basis for further research and comprehensive application. |
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