Load Spectrum And Statistical Dynamics Analysis Of Large Mining Shovel

Large mining shovel is a key digging and loading equipment of open-cast engineering and its working frontier condition, soil characteristic and operation possess strong randomness. To research this complicated random system with multiply uncertainties, it's necessary to analyze and research on test data of working site. Thus, this subject was listed as a sub-project of National 863 Project (No.2012AA062001).Based on test data from a stripping and digging site of a certain type mining shovel and combined with digging theory and analysis of abnormal cases in actual digging processes, unreasonable data were rejected. Original data was divided into several groups according to working cycle of shovel. Finally, samples with most frequency, i.e. samples with a cycle of 45s, were chose as research object.The power, torque and speed of hoisting, crowding and rotating system were analyzed in time and frequency domain. The corresponding of ensemble average, maximum and minimum value and correlation coefficients of these system parameters which reflected digital characteristic values of these systems were derived. The overload coefficient of shovel in the actual digging process according to the nominal power of motor was also obtained. For the obtained ensemble average and maximum value, a equivalent load picture was got. As the basis of further calculation, such as the calculation of soil volume in the bucket, the statistical hoisting and crowding forces were calculated.For the purpose of the further analysis, the polynomial and the trigonometric sine function form can be fitted to the discrete test data with the Lagrange interpolation. Based on the engineering requirements, the sine function is fitted to the test data of the mining section. And the autocorrelation and the spectral density function of the mining section are also obtained with the function above. Based on the comparative analysis of the time spectra of power, torque, force and speed of the hoisting and crowding system, the proportion coefficients of all parameters of the hoisting and crowding system are obtained. The solutions can guide and provide some suggestions on the design of excavator.According to the test data from the excavator working site, the average and maximum load on the bucket tooth point, namely tangential and normal digging resistance, are indirectly obtained with the theory of the mathematical statistics and the transfer function of the rigid body statics. Making the parameters of the hoisting system itself as a deterministic system, the kinetic equations of the hoisting system is built with the tangential digging resistance (?W1,?W12) as random excitation for the first time. The statistical characteristics of output are also calculated with the statistical dynamics theory (according to the average, variance, autocorrelation and the spectral density function of input).Based on the load spectrum of the excavator of this model, the load spectrum of the 75m3 mining excavator is predicted by the similarity law.