Research on all-digital strip steel rectifying electro-hydraulic control system

The simulative electro-hydraulic servo system has been widely used for rectifying system in steel industry. But the simulative electro-hydraulic servo system has the shortcoming of high cost, poor anti-pollution, high request of use and maintenance, frequent troubles and the instable working state, which could affect the product quality of strip steel and the normal production of factory. From the 1980s, the study on the digital valve instead of the servo valve and the real-time control by the computer in the electro-hydraulic control system has started. Because the study on digital valve makes little progress worldwide, it has not formed the commercial products yet at present. Thus the popularization and application for digital electro-hydraulic control system is limited. An all-digital strip steel rectifying electro-hydraulic control system successfully used in the field in China for strip steel rectifying will be introduced in this paper. This system is a complete-feedback control system, which adopts the high speed on-off ball valve as its digital valve, PWM signals as the input of digital valve, photoelectric sensor as its element for detection and feedback and PLC controller as its control device. From the theoretical analysis and field operation results of the system, it is shown that this system has not only good stability, high position precision, fast response, satisfying the performance requirement of strip steel rectifying , but also low cost, strong ability of anti-pollution and high reliability, so this system will have broad popularization value and application prospect.