Integrated Expression Of Shape Line And Structural Optimization Of Backhoe Hydraulic Excavator Bucket

Backhoe hydraulic excavator is a commonly used construction machinery in urbanization transformation,ore mining and other occasions.The working device is the most critical executive element of the backhoe hydraulic excavator,which is composed of arm,rod and bucket.As the task execution terminal of the working device of the hydraulic excavator,the bucket is in direct contact with the working object.In the working process of the excavator,the complex operating object produces random excavation resistance,which causes a certain impact and vibration to the excavator bucket,resulting in destroy to the key parts of the bucket,therefore,whether the structure of the bucket is reasonable or not has a direct impact on working efficiency of the excavator.At present,in the research field of domestic excavators,there are many researches on load analysis,hinge position,structural strength analysis and optimization of moving arm and bucket rod,but there are relatively few studies on bucket cross-section optimization and structural optimization based on shape-line equation.In this paper,takes the bucket of Pushi 21 T backhoe hydraulic excavator as the research object,and the shape structure,maximum stress and quality of the bucket are taken as the goal of optimization design.The main research contents are as follows:(1)The inner surface line projected on the symmetrical plane of the bucket was taken as the bucket shape line,and the value range of the main parameters of the shape line was studied.Taking the center of the arc at the bottom of the bucket as the origin,the bucket shape lines coordinate system was established,and the integrated expression equation of the bucket line was deduced according to the geometric constraint relation of the shape line.Based on this equation,a general optimization model of bucket shape was established with the goal of lightening weight and cutting angle.(2)Based on the bucket section curve equation,the parameterized model of 21 T excavator bucket was established by using APDL language.At the same time,the programs of meshing,constraint and load loading and strength solution were compiled.Taking the classical digging resistance as the load,check whether the bucket parameterized model was accurate or not.The influence of parameters on the stress and quality of bucket was analyzed.(3)Based on the continuous trajectory theory,when the arm was in the main excavation area,the four-segment trajectory excavated alternately by bucket and rod was selected as the continuous digging trajectory.Based on the limit digging force model,the numerical value and variation law of the limit digging force on the four-stage trajectory were calculated and compared.Under the limit digging load,the change law of bucket stress and deformation was analyzed.(4)The optimization program was compiled by enumerating method in MATLAB,and the limit digging force is used as the external load of the bucket,and the APDL command stream was called to solve it.In terms of bucket stress and quality,the results after optimization were compared with those before optimization.It was proved that the structural optimization method based on bucket shape equation in this paper is effective in improving bucket digging performance and reducing bucket manufacturing cost,and provides a theoretical basis for structural design and optimization.