Design And Simulation Of Marine Propeller Parallel Grinding Mechanism Virtual Prototype

Ship is a powerful booster for economic globalization,its core part propeller is easy to static unbalance after being machined,which will result in mechanical vibration,shafting transmission efficiency reduction and other hazards.Aiming at the problem of low automation,high difficult in large marine propeller static unbalanced allowance machining,this paper research on parallel grinding mechanism design,kinematics and dynamics simulation analysis,virtual prototype verification.The main research contents and results are as follows:Based on propeller static unbalance detection principle,different specifications of propellers are selected to carry out static unbalance detection experience.The results show that the difference between static unbalance allowance detection value and industry allowable value can be controlled within a reasonable range,and it can be removed by grinding the tolerance margin of blade surface.Combined with the experimental results and static unbalanced allowance distribution principle,a propeller static unbalance allowance processing scheme is proposed.A large propeller static unbalance allowance parallel grinding mechanism is designed.Deriving the position inverse mathematical model based on the position and posture of the end grinding actuator,then the Monte-carlo method is used to research on key structural dimensions such as external circle diameter d of moving platform,which will influence parallel mechanism workspace.The results show that when parameter d changes,the size of workspace doesn't change obviously,in order to avoid institutional interference,the value of d should be 250mm;By increasing the vertical distance h,which from the tool lower surface center point to moving platform centroid,to extend workspace on both sides of y-axis direction has no practical significance,so the value of h is 120 mm.The dynamic model of parallel grinding mechanism is established according to the Lagrange equation,then the axial driving force calculation formulas of each slider are solved based on Virtual Work principle,and the simulink simulation platform is built at the same time.The variation law of each slider axial driving force is revealed when moving platform moves in different,compound position and posture condition,that is,the numeric value and variation trend of each driving force are affected by the heave movement distance,pitch and roll angle of moving platform,the variation trend is stable in the parallel grinding mechanism dexterous workspace and its numerical value is in accordance with the actual working conditions.Building the virtual prototype model of parallel grinding mechanism in ADAMS,then the kinematics and dynamics simulation are carried out,including heave,pitch and roll motion simulation.The results show that the position inverse mathematical model of parallel grinding mechanism is accurate and effective,and its motion performance is stable under different positions and postures,no sudden point of velocity and acceleration occurred.The simulation results of virtual prototyping machine agree well with the numerical solution of Lagrange dynamics,also,the force acting on the connecting pairs is reasonable under different positions and postures,and the dynamic performance of parallel grinding mechanism is stable.