Design And Application Of Mold Level Control System For Billet Caster

In 2004, two eight-strand continuous casters had been completed in the first-stage project of steelmaking plant of Shougang Qiangang, adopting artificial casting and mold's liquid level control.To reduce intensity of work, and improve varieties of scale and quality of pruducts, two billet continuous casters had been upgraded and remolded since 2008, thus an automatic liquild level control system was increased. Mold level control is one of extremely important links in the metallurgical casting system.therefore mold liquid level must be controlled in a range.This paper anlyzed the characteristics of fuzzy control method and PID control method, and combined them organically, after that a complex controller of Fussy-PID was designed in this paper. This controller synthesizesthe advantages of both fuzzy and PID controlling modes, thus making the controller possess not only the simplicity and efficiency of the fuzzy in controlling over the non-linear system but also the accuracy of PID controlling.Based on theoretical research, by adopting Siemens S7-300 series PLC, STEP7 programming software and Intouch 9.0 configuration software in this control system, the software and hardware of upper computer and lower computer had been designed, programmed, and debugged, then the Fussy-PID complex control of mold liquid level had been realized. The method of radio isotopic detection (Cs137) was used to detect liquid level; a high-precision digital electric cylinder was used to be actuator of stopper rod, and controlled the error of mold liquid level between-5 and+5mm, and all this met requirments basically.Applications demonstrates that Fussy-PID complex controller possesses good dynamic and static characteristics and certain robustness, and the control algorithm is simple and achieved easily. In this way, the quality of casting blank is improved effectively.