Research of diagnostic system errors when determining quantities characterizing the thermal performance of ccm MOLDS
Background. A significant role in ensuring the rational parameters of the existing continuous casting machine given to the automated control systems, which ultimately should have a comprehensive monitoring and timely analysis of all parameters of CCM. In recent times, there are solutions that allow implementing quick diagnosis of heat-technological processes in the mold based on the data processing about the temperature and consumption of the cooling water in the mold. However, until now, the assessment of the accuracy of determination of desired quantities depending on the errors in measurement of values-arguments has not been implemented. Materials and/or methods. For flow meters and differential thermocouples used on a real CCM the relative error of measurement, as a rule, does not exceed 2 %. The error estimates of indirect measurements for the case when an error in the measurement values-arguments is 2% performed in the paper. For the average density of heat flow in the mold QUOTE and the average heat transfer coefficient in the mold QUOTE, the independence of the error from base-level values of G and Δ t justified. The calculations showed that in the worst case the determination error of these values does not exceed 4%. To study the error of determination of heat transfer coefficient QUOTE and the effective thickness of the gas gap d эф the functions that display a relative error of the measurements QUOTE ( Δ t), d эф( Δ t), QUOTE (G) and d эф(G) considered. For estimation of the maximum possible error, the most unfavorable cases of the results deviations of the measurement of G and Δ t considered. To calculate the errors under these conditions, we considered two baseline values of Δ t and G: Gmin=20; Gmax=30 and Δ tmin=4; Δ tmax=8. Results. It is established that at minimum values of G and Δ t the maximum possible determination error is ±5.3…5.6 % and ±6.52…of 7.97 %. At maximum - ±17.45...24.86 % and ±20.25…21.5 %. For comparison, in the limitation of the maximum possible error of G and Δ t as the 1% the following results were obtained: relative error in measurement at minimum and maximum values of G and Δ t amounted to -2.69; 2,77 % -9.43; of 11.24 %, respectively; -3.62; 3.62 % -10.28; of 10.07 %. Conclusion. The calculations showed a significant dependence of accuracy of determining the desired values by means of a diagnosis system on the error of values-arguments determination. The used approach allows determining by the calculation method the permissible measurement errors of values-arguments, providing a preset level of accuracy while setting the desired values.