Transient Mould Friction Based on the Wavelet Theory

The mould friction is an important parameter reflecting the initial shell and mould lubrication conditions. The research of mould friction is very important to the optimization and developing of continuous casting. The measured mould friction under hydraulic oscillation mode was researched with wavelet analysis to reveal its time-frequency characteristics. Firstly, the mould friction signals under different production conditions were monitored and the mould friction was calculated. Then, mother wavelet function was selected from three wavelet functions which were chosen preliminary according to the characteristics of mould friction and wavelet theory. Through wavelet transformation, mould friction signal was projected onto the wavelet domain, and the time-frequency characteristics of mould friction under different production conditions were obtained and discussed. Mould friction under different production conditions such as different oscillation mode, casting speed fluctuation, increasing and decreasing stage of casting speed and breakout occurrence was reported in detail in the wavelet time-frequency maps. The characteristics of mould friction were reflected well through wavelet transformation which proved that wavelet analysis had a good feasibility for mould friction study and can further reveal the nature of mould friction.