Structural Performance Analysis And Lightweight Research Of Large Hydraulic Excavator Working Device

In recent years,with the advancement of infrastructure construction,the construction machinery industry has developed rapidly.As a multi-functional machine,hydraulic excavator is widely used in mechanical construction such as water conservancy engineering,transportation,electric power engineering mining and etc.especially in mine excavation,the excavator with larger weight is needed to operate.Due to the problems of high fuel consumption and poor emission of large hydraulic excavators,the energy-saving technology of excavators has been studied in the context of energy shortage and rising oil prices.The working device is the executing mechanism of the excavator,and is responsible for completing various excavation operations.It has great significance to carry out lightweight research on the working device to realize energy saving of the excavator.When the large hydraulic excavator performs mining and other operations,the force of each hinged point on the working device is more complicated due to the complicated mining conditions and the variable working conditions at any time.So it is necessary to ensure the safety of the work process when the work device is lightweight designed.In view of the above problems,firstly,the structural performance of the working device is studied,and check its strength and stiffness.Secondly,the working device was lightweight designed based on the analysis results.Lastly,the strength and stiffness were compared before and after the lightweight design.The main research contents are as follows:(1)The establishment of three-dimensional model of working device.On the basis of analyzing of the structural composition and working principle of excavator and working device,the parametric model of boom with seven parameters and the parametric model of arm with five parameters was established by Solidworks referring to the size of the model and other related parameters,and then the simplified model of other components was established,finally,assembly the whole working devices.(2)The calculation of the hinge force of each component of the working device.Firstly,study the working condition of the hydraulic excavator and select three dangerous working conditions: bucket excavation,arm excavation and compound excavation on the basis of analyzing the common dangerous working conditions,and establish the position diagrams of each component under the three working conditions as the basis for the later analysis.Secondly,calculate the theoretical excavation forces according to the parameters of the hydraulic system,and apply to the corresponding excavation working conditions.Lastly,calculate the force of each hinge point under three working conditions according to the principle of moment balance and force balance,which is prepared for the later finite element analysis and lightweight design.(3)The Finite element analysis of working device.Firstly,establish the seamless connection between Solidworks and ANSYS Workbench.Secondly,carry out finite element static analysis of the boom and arm in the working device.Lastly,analyzing the strength and stiffness of the boom and arm according to the stress and deformation nephograms.According to the analysis results,the maximum stress and deformation of the boom are 239.88 MPa and 14.164 mm,and the maximum stress and deformation of the arm are178.17 MPa and 4.6420 mm under three working conditions,which are less than the allowable stress and allowable deformation.The strength and stiffness meet the design requirements.The analysis results verify the correctness of the model,and there is a lightweight space.(4)The lightweight research of working device.Establish the optimization mathematical models of boom and arm according to the response surface optimization principle.Using the response surface optimization module in ANSYS Workbench to optimize the dimensions of seven plate thicknesses of the boom and five plate thicknesses of the arm.According to the optimized solution,select a set of rounding values to obtain the optimal size of the plate thicknesses.The mass of the optimized boom and arm was reduced by 8.1% and 7.2%.(5)The comparison of finite element analysis results of working devices before and after lightweight.According to the optimized optimal solution,change the size parameters of boom and arm to establish a new boom and arm model in Solidworks.The finite element analysis of the lightweight design boom and arm is carried out by using ANSYS Workbench again.Compared with the finite element analysis results of the original model,it is found that the maximum stress and deformation of the lightweight boom and arm change little,the strength and stiffness still meet the design requirements,the correctness of the lightweight design has been verified.