Finite Element Analysis And Structure Optimization Of ARC Welding Robot

As the “Made in China 2025”plan being put forward and the state support for high-end manufacturing,the robot industry in China is developing very quicly,industrial robots have continued to emerge.Welding robot one of the most widely used industrial robots is already towards industrialization and being constantly improved.Compared with industrial developed countries,the independent research and production of welding robot in China are relatively poor in such aspects as performance, production efficiency. In this paper, on the basis of arc welding robot with the load of 10 kg, with lightweight, high stiffness and high speed performance as the goal, we completed the finite element analysis and structure optimization of the robot.First,according to the need of the research,we completed pre-processing work of arc welding robot with the load of 10 kg.We simplified the parameter model of the robot,established a structure diagram of the robot and D-H parameters,finished the detail drawing of parts and machine assembly.We made kinematics analysis and validation,solved its Jacobi matrix, layed the foundation for later propose relevant performance indicators.We analyzed the working space of the robot, it can be used as optimization constraints or one of the evaluation criteria of optimization results.Second,we did the dynamic analysis of the robot in ADAMS,found the posture when all parts work in the worst condition in the work space which the robot requires,and did the finite element analysis of in this posture. We made lightweight design for the big arm structure of robot by topological optimization method.After that,the big arm of robot gets lower weight and increased stiffness at the same time.Third,we put forward a number of performance indicators according to the requirements of robot in motion flexibility and speed stability,including the maximum distance performance workspace,static stiffness of robot and global speed integrated performance.We analyzed the coupling among these performance indicators,get the relationship among the indexes,chose the static stiffness and speed overall performance index as the ultimate optimization goal of optimization model.Sensitivity analysis of optimization can get the sensitivity of optimization goals for its variables.After determining the constraints according to the actual situation,we established the optimization function model to prepare for the size optimization below.In the end,for multi-objective optimization problem,we adopted optimal frontier methods to select optimum combination. To avoid local optimal solution,and improve the efficiency and convergence of solving,we selected the NSGA-Ⅱ optimizationalgorithm to solve the optimization model.By analyzing the optimization results, size optimization is theoretically proved to effectively improve the overall performance in speed of the robot, static stiffness properties and working space have got some improvement, two-step optimization also makes the whole robot weight decreased.We achieved the desired objective optimization.By system simulation experiment,we verified the correctness of the structural optimization.It improves that Finite element analysis, topology optimization and size optimization can make the designed robot get improved in weight,stiffness and speed,and intensity and working space meet the design requirements at the same time.