Research On Key Technologies Of Shape Control And Machinability Control In Numerical Control Machining Of Marine Fixed Pitch Propeller

In the shipbuilding industry,the propeller is a key component of the ship,and the quality of its blades directly affects the performance of the ship.The finishing in the propeller processing is to ensure that the blade has a better surface quality,and usually adopts the method of artificial polishing,the quality of the grinding process is unstable,the working environment of the worker is poor,and the labor cost is high.In order to realize the automatic processing of propeller blades,provide a good working environment for workers,and improve the machining accuracy of propellers,this paper designs a propeller blade grinding device based on a six-degree-of-freedom parallel mechanism,and designs and controls the structure for the device.System implementation,dynamic and static performance analysis,accuracy detection and error compensation,grinding allowance optimization and grinding trajectory planning research.The main research contents are as follows:Firstly,the overall scheme design of the propeller blade grinding device based on the six-degree-of-freedom parallel mechanism was completed.The kinematics analysis of the grinding device with the parallel mechanism as the main body is carried out.The accessibility analysis of the working space of the device is carried out by MATLAB software.The kinematic inverse analysis of the parallel mechanism is carried out by the geometric trigonometric function,and the positive solution is verified by ADAMS software.The grinding head is structurally designed by the selection of the grinding method.The grinding motion control system is designed and the human-computer interaction interface is used to monitor the control system.Secondly,the grinding device is simplified,the finite element model of the whole machine is established,and the static and dynamic performance analysis of the device is carried out by finite element software.The static performance of the device is good and the structural rigidity is reasonable.The device was analyzed by modal experiment and compared with the results of finite element analysis.The natural frequencies of the two were similar,and the rationality of the device was verified.Thirdly,the grinding device was tested for accuracy,and the positioning error and straightness error of the device were detected to determine the positioning error as the most influential factor of device accuracy.The BP neural network is used to model and compensate the error of the positioning error of the device,and the accuracy of the device after compensation is detected.The positioning accuracy of the final device is within ±20μm,which meets the technical requirements of blade grinding.Finally,the remainder of the propeller grinding is optimized and the grinding trajectory is planned.By analyzing the allowable error of the blade,the particle swarm optimization algorithm is used to optimize the error to determine the grinding allowance,and on this basis,the blade is divided and ground.The blade surface is calculated by the close method to determine the pose of the grinding wheel,and the trajectory is calculated to obtain the blade grinding trajectory.The blade is ground by the trajectory to make the blade reach a better surface quality.