Design And Key Technology Research Of Large Marine Propeller Machining Robot

As the core component of ship power system,the propeller’s manufacturing level and processing quality have a direct impact on the safety and stability of ship operation.With the rapid progress of robot technology,industrial robots are more and more widely used in manufacturing.Using industrial robots instead of CNC machine tools to complete large marine propeller processing can significantly reduce investment costs and promote the development of SMEs.In this context,the large marine propeller processing robot was studied and a 2P4R six-degree-of-freedom industrial robot for processing large marine propeller blades was proposed.Based on this robot design scheme,the kinematics workspace of the robot,the forward kinematics and trajectory planning simulation of the virtual prototype,the statics and modal analysis of the robot are studied.The specific contents are as follows :(1)According to the enterprise processing requirements and propeller processing difficulties,the working requirements of the robot were determined.The overall scheme design and transmission scheme design of the robot were completed based on the reference of a variety of configuration robots and transmission systems.UG software is used to complete the establishment of the three-dimensional model of each component of the robot and the assembly of the whole robot.According to the actual load and other parameters,the selection and calculation of the key components such as the ball screw,servo motor and reducer of the robot were carried out,and the basic parameters of the robot were finally determined.(2)Taking the end-effector into account,the forward kinematics mathematical model of the robot was established by using the improved D-H method and the forward kinematics equation was obtained.Based on the Monte Carlo method,in the Matlab environment,the workspace of the robot was solved by using the robot toolbox in the Matlab software,and the point cloud of the reachable workspace of the end cutter of the robot was depicted.The results of comparing the surface fitting with spatial tolerance showed that the designed 2P4R six-degree-of-freedom propeller processing robot can cover the upper surface of a single blade of a large marine propeller with a diameter of 5-9 meters,and the working range meets the requirements.It lays a solid foundation for the subsequent research on the processing trajectory planning of large marine propeller processing robots.Finally,the inverse kinematics solution of robot is deduced by inverse transformation method.(3)The forward kinematics simulation and trajectory planning simulation of the virtual prototype of the robot were carried out by using ADAMS software.The changes of parameters such as displacement and velocity of the reference point of the end tool of the robot with time and the changes of parameters such as angle and angular velocity of each joint with time were obtained.The reliability of the robot design is verified by analysis.(4)Through the finite element analysis software ABAQUS,the static analysis and modal analysis of the four postures of the large marine propeller machining robot are carried out.The maximum stress of the robot,the offset of the milling cutter,the first six natural frequencies and the corresponding vibration modes of the robot are obtained.The weak links of the robot stiffness are identified,which lays the foundation for the optimization design of the key components of the robot.