Experimental Research On The Influence Of Process Parameters On Performance Of Robotic Milling

The application of industrial robots for milling processing has the superior position in large processing range,flexibility and speed compared with traditional multi-axis milling machining centers,and it features prominently in the field of large components in aerospace.However,the milling performance of a robot in a certain posture is extremely sensitive to process parameters due to the influence of their own open-chain multi-rod serial structure of the robot system.Improper milling process parameters will easily cause large-scale fluctuations in machining accuracy.Choosing reasonable milling process parameters can greatly improve the milling performance of the robot,which helps to overcome the deficiencies of industrial robot milling.Therefore,the 7075-T651 highstrength aerospace material was served as the research object,and this study investigates the effects of parameters on the performance of robotic milling by designing and building an experimental platform for robotic milling.The main research contents are as follows:Firstly,the detailed derivation and research of the robot kinematics and stiffness analysis were carried out.Through the D-H method,the robot kinematics model was obtained,and the forward and inverse solutions of the robot kinematics have been studied.In addition,this paper also deduced the Jacobian matrix in the coordinate system of the robot end,and then analyzed the stiffness of the robot system,including the derivation of the robot joint stiffness identification process and the derivation of the robot end stiffness matrix.Then,the design and analysis of the robotic milling test system have been carried out.According to the robot’s load requirements and milling performance requirements,a suitable high-speed motorized spindle was selected and a motorized spindle fixture matching the spindle was designed.Then,a robotic milling processing test system was built,and the tool coordinate system of the test system was calibrated by off-line programming software to reduce the error in the practical application of the robotic system.For the stiffness of the robot system,the stiffness value of each joint of the robot was obtained through the identification experiment.The exploratory experiment was conducted on the influence of the stiffness of the robot system.Then,the modal analysis and experiment were carried out by the hammer method and acquired the modal parameters.Finally,the robot milling experiment and the research on the effects of process parameters have been investigated.Based on the milling test system,the 7075-T651 aircraft aluminum alloy plane end milling test was conducted under dry conditions,and the experimental research was considered on the milling load,workpiece surface quality,milling vibration and machining stability.The effects of parameters on the robotic milling performance under multi-factors were explored from the above three aspects based on orthogonal method,and the effect of each parameter was quantitatively evaluated.Combined with the results of the milling test in this paper,the optimal process parameter combination in this study was selected,and the verification experiment of the optimization results of the robot milling parameters was carried out.