ROLL LOAD MEASUREMENTS ON THIN SLAB CASTER FOR LIQUID-CORE DETECTION

Measurements of roll loads with strain gauges implemented on roll gird ers were carried out on a thin slab easter. Numerical calculations and shop tests indicated the applicability of this measurement arrangemen t. It has to be considered under the specific aspect that, owing to th e low design height of thin slab casters, the occurring loads are cons iderably smaller than in standard slab casters. The evaluation of the measurement data obtained during operation of the thin slab easter was done from two main viewpoints. First, it was of interest whether it i s possible to measure the presence of a liquid core at a given distanc e from the meniscus. Second, the measurements were supposed to be used for verification of the liquid core position calculated on line by Dy nacs(R), VAI's dynamic cooling model. Essential difficulties in evalua ting the data originated from the changing thermal and mechanical load s. The slowly changing thermal loads that are superimposed on the mech anical loads make it impossible to determine the presence of a liquid pool simply by checking the strain gauge signal and comparing it with results collected during the shop tests. Mechanical load changes at re latively high frequencies occurred owing to varying roll forces even w ith minor eccentricities of the rolls. Thus, checking for critical val ues of the load changes also seems impractical. For on line prediction of the liquid core position, a combination of numerical estimation of the liquid core position with on line thermal tracking as an approxim ate approach and measurements for exact prediction seems to be the mos t promising strategy. An interesting alternative to this strategy coul d be the on line evaluation of fast Fourier transformed (FFT) strain g auge signals. IS/1344 (C) 1998 The Institute of Materials.