Load Spectrum And Digging Trajectory Analysis Of Large Mining Shovel

Working boundary conditions of large mining excavator,properties of digging soil and operation to the excavator of the operator present strong randomness.Analysis of data,which is measured during the excavator's working time,is needed to study the load spectrum of the complex system.The results of dynamic response in digging system could make the system compoents generates dynamic stress,lead to material fatigue damage and endanger system safety.Dynamic response can also cause excessive dynamic deformation and acceleration,which affect the normal operation of the machine.In addition the pros and cons of digging trajectory directly influence the performance and production efficiency of mining.Therefore,excavator load spectrum,the dynamic response and digging trajectory,to improve the work performance of excavator is of very important significance,was listed as one of the national 863 project(No.2012AA062001).On the basis of WK35 mine excavator measured data on stripping excavation site,samples are divided into groups by digging time.Ultimately samples of most frequency(period of 11s)are selected as the research object.Power,torque,rotating speed of pushing and hoisting system are analyzed,and then the average value,most value and median value of the system parameters are obtained,which reflect system's operating characteristics.Time domain diagrams are mapped.Statistic values including hoisting force,pushing force,hoisting speed and pushing speed are also calculated,which provides the basis for subsequent calculations.Discrete data of average and maximum are fitted into the form of sine function,and autocorrelation function and spectral density function are also worked out,which provides convenience for application in statistical dynamics.For vibration problem of large excavator's digging system,vibration model containing movable arm and bucket rod two degrees of freedom is determined.Digging resistance in shovel bucket pointe regarded as random incentive,Lagrange dynamic equations are established to calculate the vibration response of mining system.In order to achieve low loss and highly efficient mining,digging trajectorys of WK75 type excavator are predicted under three different kinds of soil.Through the establishment of different initial conditions and boundary conditions,mining path expressions are concluded by using Matlab program.By changing the length of the connecting rod,rear angles in digging under different location points are calculated.Finally,after the parameters given,length of the connecting rod would be obtained.The mean length of connecting rod provides theoretical basis for practical mining.