Mechanical Properties Analysis Of Key Componets Of Excavator

Working device and slewing piatform asthemaincomponentsufferedforceloadingof hydraulic excavator,its performance in all aspects has an important impact on the overall performance and operational reliability of excavator. The loads of which bore by the working device and slewing piatform have changed violently in the digging process because of the complexity of the job object andthe variability of digging gesture.If the excavators work in harsh environments for long hours, fatigue cracks will occur and even fracture in the position of the stress concentration in key components such as the boom,the arm and the slewing piatform etc.Therefore, the anasysis of key components’ s intensity of hydraulic excavator by the finite element method is necessary.Finite element analysis had been carried out for working device and slewing piatform of the hydraulic excavator which weights almost 21 tons in this issue, and then the danger positions of the main components of working device were determined, which provide a reference for load spectrum test of excavator. The gesture of indoor loading test for excavator was defined according to finite element analysis results and indoor load test requirements, and the relationship between the load and the stress of main component was determined by applying different forces to the finite model for working device and slewing platform to provide a reference of applying loads for fatigue test.First, digging resistance, the theory digging force and lateral force were analyzed according to the excavator job object, cutting process, restricted factors for mining and partial load circumstances; Seven typical mining stance were determined and theory digging force and lateral digging force for each digging gesture was calculated.Secondly,the whole finite element model of working device and slewing piatform was establishedwhichhydraulic cylinder was seen as link element and hinged connection dealt with the method of coupling nodes, and the analyses for every gesture at average load condition and partial load condition were carried out,the danger positions in boom,arm and slewing piatform were determined. The results show that the danger position in the boom were located in the welding of ear plate and the boom, the welding of boom and the bushings of the pins which connect boom and boom cylinder.The danger position in the arm were focused on the hinge hole which connects the boom and the arm and where the hinge hole located in.The danger position in the slewing platform are located in the welding of the slewing platform and the ear plate which connected with the boom cyclinder,the welding of the slewing platform and the ear plate which connected with the boom.Finally, the digging gesture 3 and 7 were selected for indoor fatigue loading test,based on the results of finite analysis for tangential force, normal force of different sizes applied individuallyand the two forces were applied, in the same time, several positions in the boom and arm were chosen to extract stresses to determine relationship of stress-load of the selected positions.