Stiffness Analysis And Optimization Of Robot Milling

Based on the industrial robot system of low cost,good flexibility and the advantage of high automation,make it have broad application prospects in the field of mechanical processing,but limited to traditional tandem industrial robot mechanical structure and the characteristic of the weak stiffness,which often face in the process of machining mechanical deformation problems,which often leads to insufficient system processing precision and the processing quality is unqualified.In order to ensure the stable and reliable milling process of series robots,and to ensure the processing quality,this thesis mainly carries out the following research:Firstly,according to the mechanical composition and basic parameters of ER20-C10 industrial robot,the improved DH parameter method is used to determine the robot kinematics model,and the forward and inverse solutions of the model are solved.Based on this theory,the Jacobian matrix of the robot is constructed by using general vector method.The spindle fixture is designed by Solidworks 3D software,and the coordinate transformation relationship between the tool coordinate system and the robot coordinate system is determined,and the force at the center point of the tool end is transformed to each revolute joint of the robot.Orthogonal simulation experiments were carried out by using metal cutting software Advant Edge.An empirical model of milling force was established through multiple linear regression equation analysis,and significance level was tested.The mapping relationship between the end-milling force of the robot and the force at the rotational joint was established by using Newton-Euler equation considering the influence of gravity on the robot connecting rod.Secondly,by simplifying the internal transmission parts of the robot revolute joint to elastic elements,the equivalent stiffness values can be calculated,and all of them are converted to the output end of the joint,and the output end stiffness of each revolute joint is mapped to the end flange of the robot by jacobian matrix.The robot connecting rod is simplified as a flexible rod,and the deflection matrix of a single robot connecting rod is established by bernoulli-Euler beam theory,and the deflection errors of each robot connecting rod are mapped to the end flange of the robot using the error transfer model.Finally,the stiffness model of ER20-C10 industrial robot is established by summing the joint deflection and the link deflection vector.Finally,using the monte carlo method on workpiece space robot simulation,and combining the robot stiffness model to calculate the robot end flange of the deflection values,with the deflection value as the evaluation index selected robot milling the optimal position,on the basis of the optimal position of robot milling path for discrete,and forecast error path of discrete points,the error compensation model of the robot can improve the milling quality and reduce the workpiece surface error.