Structure And Control Optimization Of Large Mining Excavators

Large mining excavators have been widely used in coal mines,iron ore mines and other open-pit mines,with high efficiency,good construction stability and strong environmental adaptability.However,the operation of excavators has been completely dependent on workers’experience for a long time,which not only has low efficiency,but also has high energy consumption.Therefore,the optimization design for large mining excavators has gradually become the research focus of relevant research institutions in various countries.The traditional optimization design of excavator was mainly aimed at the lightweight design of front-end working mechanism,which designed with the main mechanical structure of the excavator as the design variables,the weight as the optimal target and the stress and fatigue life as the constraint conditions.In most cases,the optimal control design was carried out after obtaining the optimal structure.This method can only realize the local optimum of the structure parameters or control parameters,but not the best of both.Therefore,this paper proposed a method,which can guarantee the lowest energy consumption and maximum mining efficiency in digging process.The structure parameters and control parameters of the front-end working device of excavator were optimized based on the comprehensive consideration of the Angle distribution of the pile.The main contents of this paper are as follows:Firstly,the characteristics of interaction resistance between bucket and excavated materials were studied in digging process.And a dynamic mining resistance calculation model was built,which considered the gravity of material and bucket,the friction between material and bucket,the influence of mining speed and material on both sides of bucket.By compared with the actual excavation resistance,this model has high precision and can meet the optimization design requirements of the excavator.Secondly,the mathematical model of excavating trajectory of large mining excavator was studied,and the unperfection of the traditional logarithmic spiral trajectory theory was analyzed.Then,the mechanical kinematics method was used to synthesize and decompose the hoist speed and crowd speed of the excavator,and obtained the mathematical model of mining trajectory related to the control parameters of excavator.Based on the new mining trajectory model,the mathematical model of cutting Angle,Angle of excavation,mining thickness and volume of excavation were derived.Then,the optimization model was established by using the proposed mining resistance calculation model.The product of energy consumption of excavating unit weight materials and the mining time were used as the objective function,the structure and performance parameters of the excavator were used as constraints,and three different angles of 38~?、43~?、48~?were considered,in this model.The model was applied to the control parameter optimization of wk-55 excavator,and the optimal control parameters were obtained.Finally,the main structural parameters affecting the performance of excavator were analyzed.Then the optimization design was carried out,and the structural parameters and control parameters were used as design variables,the product of mining energy consumption and excavation time was the optimization objective function,the excavator performance parameters and mining process parameters were used as constraints,in the optimizating design.Compared with the traditional optimization design method,a better optimization result can be obtained by optimizing the structure parameters and controlling parameters.