Research On The Key Technology Of Blade Milling Machining Robot For Large Distance Marine Propeller

As the core structural component of ocean-going ship power system,the manufacturing level of large-scale fixed-distance Marine propeller directly affects the stability of sea navigation.With the continuous development of machining technology,the machining method of large-scale fixed-distance Marine propeller has gradually developed from manual machining to automatic machining.Robot machining is widely used in manufacturing because of its high flexibility and low cost.However,due to the poor stiffness,the general six-axis industrial robot can not meet the requirements of high efficiency rough machining of large-scale fixed-distance propeller blades.In this context,this paper analyzes the necessity of designing a special robot for high efficiency rough machining of large distance propeller blade,and expounds the design idea of new robot machining scheme from the relationship between machining stability and machining efficiency.Based on this,the scheme design,kinematic and dynamic modeling analysis,static and dynamic characteristics analysis and optimization of large-scale fixeddistance propeller blade insertion and milling machining robot are carried out.The specific contents are as follows:(1)The reason why the universal six-axis industrial robot can not be used for efficient machining is analyzed.Based on the deficiency of traditional machining technology,the interpolation and milling machining scheme is proposed.According to the processing technology,the structure of the cutting-milling robot was reverse designed.According to the processing index of the subject,the main parts of the robot are selected,and the related processing parameters are drawn up.;(2)Based on the structure of the robot,the forward kinematics equations and inverse kinematics were established considering the end-effector.The kinematics simulation was carried out by Matlab,and the cloud image of the robot workspace was obtained by Monte Carlo method,and then compared with the point cloud image of the propeller area to be processed.The results show that the designed robot can meet the processing range of blades with a diameter of less than 9m;(3)The Lagrance method was used to model the dynamics of the robot.Based on this,the virtual prototype of the robot was established in ADAMS,and the dynamics simulation of the robot and the end milling cutter reference point trajectory simulation were carried out,and the dynamic parameter curves of the robot end reference point and each joint were analyzed.The results show that the motion state of the robot can meet the machining requirements of the blade of large distance Marine propeller,which verifies the reliability of the robot design;(4)Aiming at the low stiffness of robot,a joint stiffness model was established and the main influencing factors were analyzed.Based on this,three key poses were selected to analyze the static and dynamic characteristics of the robot.According to the simulation results,the machining process is optimized and the weak parts of the robot are analyzed.Then the topology and size of the fuselage and manipulator are optimized respectively.The results show that under the premise of ensuring the static and dynamic performance of the robot,the overall weight of the robot can be reduced to 1218.54 kg,which optimizes the robot structure and improves the machining stability.