Optimal Design Of Backhoe Hydraulic Excavator Working Device Based On Synthesis Digging

As the mainly machinery in the field of engineering machinery, hydraulic excavatorplay important roles in engineering construction, such as road construction,urban planning and Energy Base Construction. Working device is core system ofhydraulic excavator and its digging performance is an important symbol of the wholemachine design level. In order to solve the problem that domestic hydraulic excavator inthe real working process reveals insufficient digging force， inefficiency and poor fueleconomy, a new optimal design method for working device of hydraulic excavatorbased on synthesis digging is proposed while domestic hydraulic excavator is alwaysdeveloped based on advanced excavators from overseas.Characteristic digging trajectories back-calculated from multiple test datademonstrate that complex digging and arm-digging play important roles in actualdigging process, and the customary digging paths of different excavators vary withdifferent digging object. The specific methods of synthesis digging include thecombination of single-cylinder digging trajectories as a customary digging path andcomplex digging of two active cylinders on a point in feasible area. The diggingperformance gap between domestic and abroad excavators calculated with new diggingperformance analysis method based on synthesis digging can explain the reason to theperformance deficiency of domestic excavators, which proves excavator diggingperformance is calculated more accurately with the new analysis method. And thenbased on the new digging performance analysis method, the optimization mathematicalmodel is built to ensure the digging force and fuel economy of developed excavators asgreat as possible by extracting some hinge points layout parameters of working deviceas design variables and adding some effective constraint function. The optimizationmathematical model is built and the multi-objective optimization is solved by using ofgenetic algorithm. The optimization result shows that a certain model of a excavator’smaximum digging force on the customary digging paths is improved by10%, theproportion of two active cylinders when giving full play in complex digging process isimproved by13%and the maximum complex digging force is improved by8%after theoptimization on the working device of the excavator with weak digging force, whichproves that the new optimal design method based on synthesis digging is feasible toimprove the digging performance of hydraulic excavator. At last, the interactive optimization software based on synthesis digging method is compiled by Visual Basiclanguage and it will provide a better platform for the research and development ofexcavators.The main contents of this paper are listed as follows:①After mechanical analysis and kinematic analysis on the digging characteristicsof hydraulic excavator’s working device, the mathematical expressions of hinged pointcoordinates and the size of the whole machine digging force are presented by setting upthe mathematical model of the hinge point and forces model of the working device,which provides theoretical basis for digging performance analysis.②Compared to some commonly used excavator digging performance analysismethods and the corresponding optimal design methods, modeling idea and feasibilityof a new excavator digging performance analysis method based on synthesis digging areproposed in detail, and then performance analysis and optimization software iscompiled by VB language.③Apply the new performance analysis method to a36t domestic hydraulicexcavator and the benchmarking product, and then compare their digging performanceto verify accuracy of the new performance analysis method, such as the size ofsingle-cylinder digging force on their customary paths, proportion of the diggingcylinder given full play, the size of complex digging force in feasible area andproportion of the complex digging cylinders given full play.④A new optimal design method is proposed based on the new diggingperformance analysis method, and its feasibility is verified through applying the designmethod to the weak excavator to develop advanced excavator with better diggingperformance.