Prediction Approach of Bulging Position and Deformation Based on Hilbert–Huang Transform in Slab Continuous Casting

Abstract

Bulging is the typical shape defect of continuous cast slab, which could often lead to center segregation, shrinkage porosity and slab cracks, even causing casting interruption in severe cases. Online prediction for the bulging is of great significance for stabilizing and improving slab quality. Up to now, there are few mature or reliable approaches to predict the accurate information of bulging’s position and deformation. Taking into account that the bulging is closely related to the periodic fluctuation of mold level, this work applied Hilbert–Huang Transform method (HHT) to extract and investigate the periodic fluctuation characteristics, bulging frequency and fluctuation component of mold level caused by bulging. The position and deformation of bulging are predicted with the frequency and amplitude of the component mentioned above. The results informed that the proposed method could accurately detect and locate the position of bulging, and the predicted results of bulging deformation were consistent with that of empirical equations. Meanwhile, the abnormal periodic transverse depressions on the slab surface could also be detected. The proposed approach for slab bulging prediction based on HHT does not need to install additional sensing and measuring elements, which provides a feasible way for predicting position and deformation of bulging.