Mechanical response of continuous casting billet machines - Part I : Sensors and basic machine response

Mold interaction with the billet, both thermal and mechanical, governs billet quality and productivity. The heat extraction capability of the billet mold has been well addressed in the literature, but the mechanical response of the mold, also fundamental to the process, remains less studied. The main objectives of this study were to quantify the mechanical response of the mold with force and kinematic sensors. In the first part of this two part paper, the basic machines response, as measured by linear variable displacement transducers, strain gauges, oscillator motor current, load cells and piezoelectric strain sensor are presented. Measurements were conducted on two continuous casting machines over the course of five plant trials. Some of the major findings include significant differences between operating and design stroke, resulting in variations in negative strip time. The oscillation stroke was frequently not a perfect sinusoid during casting, resulting in values of negative strip time that differed from the computed values based on sinusoidal mold oscillation. Perhaps the most important outcome of this study was that strain gauges, which are easy to install and robust, are very effective in monitoring machine loading and provide a quantitative measurement of forces. Although the form of the signal is comparable to those obtained with load cells installed in the mold housing, the latter provide a relative measure of force as compared with strain gauges which give absolute force. A new piezoelectric strain sensor was also tested during the trial and was found to be less sensitive than strain gauges.