Research On Design And Dynamic Performance Of A Novel Welding Robot

With the continuous progress of mechanical manufacturing technology,modern welding technology will gradually move towards high-speed,precision and intelligence.Using robots instead of manual welding has become an inevitable trend of intelligent development of manufacturing industry.Existing welding robot mechanisms mainly include series and parallel mechanisms.Series welding robots usually install driving elements at joints.Their structure and control are relatively simple,and their workspace is large,but their stiffness and load capacity are low.Parallel welding robots adopt multi-branched structure,which is complex and limited in workspace,but with high stiffness,better welding accuracy can be obtained.Based on the characteristics of two types of welding robot mechanisms,a new type of welding robot mechanism is designed in this paper.The parallel link system with two degrees of motion is used as the base,the open chain in series is used as the welding joint,and the slider is used to change the length of the frame and increase the workspace of the welding robot.The design analysis and dynamic performance of the mechanism are carried out.The main contents include:According to the design requirements of welding robot mechanism,the original embryo diagram scheme is determined,and all types of embryo diagrams are enumerated by the method of embryo diagram insertion points.According to graph theory,the optimal two-degree-of-activity nine-bar linkage mechanism is selected as the initial embryo diagram,and the kinematic chain diagram and mechanism diagram are transformed to determine the configuration scheme of the new welding robot mechanism in this paper.The dimension analysis of the welding robot mechanism is carried out,and the bar length constraints between the rods are quantitatively analyzed,and the design scheme of the welding robot mechanism is obtained.Based on the screw theory,the degree of freedom of the designed welding robot mechanism is calculated,and the number of working degrees of freedom is obtained.The D-H parameter method is used to establish the linkage coordinate system of the welding robot base,and the forward and inverse kinematics solutions of the output end of the mechanism system are solved by matrix transformation.The singularity of the mechanism is analyzed by Jacobian matrix.The positive solution equation and velocity equation of the end point of the mechanism are simulated numerically,and the position curve,velocity and acceleration curve of the key points of the mechanism,as well as the workspace of two different working conditions are obtained,which can provide reference for the reasonable selection of working conditions in engineering.Based on kinematics analysis,the dynamic equation of the mechanism system is constructed by Lagrange method,and the dynamic equation is solved numerically by the fourth-order Runge-Kutta method.The components of the welding robot are regarded as elastic bodies.The elastodynamic model of the welding robot mechanism system is established by finite element method.The elastodynamic model is analyzed by Newmark method.The elastodynamic performance of the mechanism system is analyzed and an example is given.The virtual prototype model of a new type of welding robot mechanism is established,and the virtual simulation analysis of kinematics and dynamics is carried out.Compared with the corresponding numerical simulation analysis results,the rationality of the theoretical analysis is verified.