The DEM Research On Crowd Force Of Face-Shovel Hydraulic Excavator

For the fuel consumption,Construction machinery industry is second only to automotive industry.Energy-saving and emission-reduction is the heart in the development of construction machinery,while the large-scale is one of the main methods for construction machinery energy saving.In response to the domestic demand,developing large excavator is urgent.In domestic,the research and development(R&D)for the excavator larger than 200 t is still in the initial stage.Due to lacking of the evaluation method for bucket crowd force and data accumulation,the analogy method is the only method for the domestic machine design and power system matching,which leads the similar products is larger and higher energy consumption than foreign products.Therefore,based on the application of discrete element method(DEM),a more accurate numerical simulation method for the research of large tonnage hydraulic excavator crowd force was proposed,and the analysis about crowd force was done.The specific contents are as follows:The multi-body dynamics model of working device for large face-shovel hydraulic excavator was established,analyzing the working device movement position and gesture of typical working conditions like bucket rod mining.The physical properties of ore material were calibrated,and it established the DEM model of ore.Through analyzing the angle of repose for ore heap,it verified the ore model in simulation method.Based on kinematics model of bucket rod mining condition,it set the movement parameters of working device and simulated ore mining to get the bucket crowd force.The crowd force was loaded into dynamics model of working device,which to analyze the force of working device and verify the reliability of the crowd force assessment methods by comparing cylinder pressure between simulation and experiment.In this way,it provided the data support for the working device and the hydraulic system design.Based on the DEM model of ore,the bucket crowd force was analyzed.It studied the force distribution on bucket,the results suggested that the cutting resistance on bucket tip is an important part of the crowd force.Through analyzing the crowd force of bucket rod mining condition,the three factors of the crowd force was determined.It studied the influence of different mining back angle on crowd force,and got the optimal back angle of bucket rod mining condition.The crowd force and digging force were analyzed and compared,which providing guidance for excavator working.The working device dynamics model was further refined.Through the parameterization of working device hinge point and loading the crowd force,it studied the influence of hinge point location and cylinder pressure on digging force,optimized the design of working device and improved the mining efficiency.