Optimization Design Of Working Device Of Ultra-Large Shovel Hydraulic Excavator With Horizontal Oil Cylinder

Ultra-large hydraulic excavator is a major technical equipment in large-scale open-pit mining engineering and large-scale infrastructure construction.It has a development history of about 50 years in the world,and its technical level is mature.It is mainly manufactured by several professional enterprises in the United States,Japan and Germany,but only a few professional enterprises in China have manufacturing capacity.However,there is a big gap between the research and development time,theory and key technology and the international advanced technology.By studying the design concept and mature industrial technology of ultra-large shovel hydraulic excavator,it is of great significance to complete the optimization and upgrading of the technical structure of excavator products,accelerate the development of domestic excavator industry and enhance its international competitiveness.In this paper,the working device of ultra-large positive shovel hydraulic excavator(also known as auto-leveling mechanism)with horizontal hydraulic cylinder is taken as the research object.Based on the knowledge of mechanism and mechanical dynamics,the theoretical model of auto-leveling mechanism of working device is established.According to the structural characteristics and working principle of automatic leveling mechanism,the performance parameters of positive shovel working device are analyzed in detail.In order to improve the horizontal pushing performance,a multi-objective optimization model was established to minimize the displacement variation in the vertical direction of the tip of the bucket tooth and the change of the cutting Angle.The MATLAB genetic algorithm was used to optimize the main parameters of the excavator working device,and the TOPSIS method was used to screen out the expected optimal solution.A three-dimensional model was built with the optimal results in SOLIDWORKS,and the kinematics and dynamics simulation was carried out by Adams.The mining envelope diagram was drawn to verify the motion characteristics and horizontal pushing effect of the optimized model.The theoretical model of horizontal pushing pressure is established,and the variation law of excavation resistance during pushing is analyzed.According to the change law of excavation resistance,the excavation resistance and material gravity were added to the dynamic simulation to simulate the actual pushing and pressing conditions,and the energy consumption model of horizontal pushing and pressing movement was established from three aspects:overcoming the work done by the load,kinetic energy of the working device and the change of gravitational potential energy.The simulation results show that the optimization scheme improves the mining performance.In the second stage of horizontal pushing and pressing,the hydraulic cylinder of the bucket rod can be operated independently to complete the pushing and pressing condition,simplifying the pushing and pressing operation.The whole pushing and pressing trajectory is close to the ideal target,the maximum displacement of the vertical direction of the tip of the bucket is less than 0.5%,and the total change of the bucket after cutting Angle is less than 2~°.The automatic leveling mechanism can realize energy recovery and reuse and has obvious energy-saving effect.