Известия Томского политехнического университета: Инжиниринг георесурсов (Sep 2017)
Identification of distribution laws of working time and recovery time of grinding equipment
Abstract
The relevance of the discussed issue is caused by the need to identify distribution laws of working time between neighboring failures and recovery time of equipment of ore grinding technological system (OGTS), which are used when developing a computer model to assess and analyze its functioning efficiency, taking into account the equipment reliability. The main aim of the study is to identify the distribution laws of working time between the neighboring failures, recovery time and to assess the exploitation reliability of grinding equipment based on statistic data on failures and recovery of the failed equipment of OGTS at Zangezur copper molybdenum combine (ZCMC, Armenia). The methods used in the study: theory of reliability, methods of applied statistics, modeling methods. The results. The author has substantiated the necessity of identifying the distribution laws of working time probability between neighboring failures and recovery time of grinding equipment based on the experimental data. The statistics on failures and recoveries of grinding equipment of OGTS ZCMC for three years of their exploitation was collected. Using a non-parametric Wilcoxon test and the Kruskal-Wallis test the author checked the hypotheses on homogeneity of statistical sampling for the same type of equipment. Based on statistic data, applying the Pearson's criterion of agreement the author identified and mathematically described the density functions of time distribution between the neighboring failures and recovery time of the failed grinding equipment. On the basis of the developed histograms of working time between neighboring failures and recovery time of grinding equipment the author put forward the hypotheses on the laws of their distribution, considering the exponential distribution, Weibull, lognormal and Rayleigh distributions as hypothetical distribution laws. The identified distribution laws are required to develop the OGTS computer model, which allow investigating the impact of reliability indicators of grinding equipment on the system functioning efficiency. The author determined the estimations of the parameters of the identified distribution functions, the average working time between the neighboring failures, the mean time to repair and built their confidence limits. The estimates of the main quantitative indicators of grinding equipment reliability were determined as well.
