Research And Application Of Quality Estimation System For Continuous Casting Slab

The online quality estimation of continuous casting slab is a new technology to determine the online quality defects of slab since 90’s of last century, which is important to the casting quality control. According to the characteristics of two-strand slab caster designed by Austria Steel, the related quality data were sampled from PLC and server on level 2 on the basis of the analysis on the cause of the slab quality defects, the knowledge base is established and the inference method is discussed based on the fuzzy rules, at last the scout and quality estimation system of continuous casting slab is accomplished.The main works in this dissertation are as followings:(1) Analysis of principle and influence factors of slab quality cracks, establish the relevance of quality cracks and key production process data.(2) Acquisition key process parameters data from desulfurization station, reladling station, BOF, LF, RH, CAS, casting machine in steelmaking process.(3) Establish the quality control model and knowledge base based on the fuzzy rules according to the processing technique requirement of different steel grades, which made the rules on the knowledge base can be classified by steel grades and increased the accuracy rates of estimation.(4) Study the method of forward inference and inverse inference, and complete the online estimation of the internal and external quality defects, especially accomplish the scout of the slab quality by querying the processing data and inverse inferring.(5) Develop the scout and quality estimation system for continuous casting slab with Visual C++, relative database and real-time database, which including the following core modules:the data adapter module, the quality event trigger module, the quality tracking module and the slab quality expert system knowledge base module and so on. The rules in the knowledge can be added, deleted and modified according to the analysis of the field data.The system test on-line showed that quality estimation has perfect performance on the quality judgment about the center segregation, subcutaneous bubble, surface defects and non-metallic inclusions, but it is not very accurate for internal quality cracks such as center porosity, shrinkage, center crack, internal crack, and corner crack, which still need further improvement on this field.The quality estimation online system can make ensures to supply the high level quality of slabs to 1580 and 2160 hot rolling mill and improves the slab continuous casting machine product quality, hot delivery rate and reducing the energy consumption. The roller mill operator can take corresponding measures in rolling mill process based on the slab quality judgment results, and ensure production smooth and controllable.