The Analysis And Optimization Of Crowd Reducer Of Large Mining Electric Excavator

Large mining electric excavator is the main excavating equipment used for open-pit mining.The digging action of excavator is realized by cooperation of crowd mechanism and hoist mechanism.Crowd reducer is an important component of excavator crowd mechanism,and plays an important role for the realization of digging action and transmitting crowd force.Therefore,it is very necessary to make a special study on crowd reducer of large mining electric excavator.The current research situation and development trend of electric excavator,working principle of excavator and its crowd reducer are introduced.And combined with the spectrum of excavator crowd force,gears,shafts,bearings and box of crowd reducer are analyzed and optimized.Analysis of gears of crowed reducer including analysis of gears fatigue strength(contact fatigue of gear surface and bending fatigue of gear dedendum)and comparison analysis of gear stiffness based on the Ishikawa method and finite element method.The strength and stiffness analysis of the shafts of crowd reducer has been completed.And on this basis,modification(including axial modification and profile modification)of driving gears of crowd reducer is completed;Analysis of rolling bearings of crowed reducer including analysis of internal load distribution of bearings,analysis of internal contact stress of bearings and impact analysis of crowd force and crowd speed on lubrication condition of bearings;Analysis of box of crowed reducer including static finite element analysis and modal analysis of box.And on the basis of static analysis of box,topology optimization of crowd reducer top box is completed.Furthermore,impacts of topology optimization of crowd reducer top box on reducer performance(including stress of reducer box,life of rolling bearings and stress of gears)is studied.In order to under the premise of satisfying the transmission performance requirements,lightweight of the top box of crowd reducer is achieved.The analysis results are as follows.The gears and shafts of crowd reducer satisfy the strength requirements in the digging process;Compared with the gears stiffness calculation results of FEM,the calculation results of Ishikawa method are conservative;The internal contact stress values of the rolling bearings are less than the allowable stress values,which meet the requirements of contact strength;Compared with crowd force,crowd speed has a more obviously impact on the lubrication condition of rolling bearing of crowd reducer;The modification of driving gears of crowd reducer plays a positive role in relieving the eccentric load,reducing the edge load of tooth surface and relieving the impact phenomenon in the transmission process.Topology optimization of crowd reducer top box has little impact on the life of the rolling bearings,but has some impact on the stresses of gears and the stress of box,which satisfy the design requirements.