Research On Key Technology Of On-Machine Measurement In Propeller-Surface-Polishing NC Machining

Marine propeller is the key component in large-scale ship. The machining accuracy of marine propeller directly influences the propulsive efficiency. However, because of the large scale and the complex shape of marine propeller, it is very difficult to process the marine propeller. At present, the multi-axis CNC machine is used to mill the workpiece, and the processing of polishing by fitter is still used in finish machining. The low efficiency and the bad quality of processing takes several months to complete a propeller.Based on analyzing the current status of marine propeller machining on CNC, the propeller fixing method by using laser displacement sensor was researched, and the deviation of propeller fixing was get; according to the geometric features of marine propeller, a rotary-section-line-based scanning method was researched. The scanned point cloud data can be obtained quickly by using this method, and it is efficient to simplify the scanned data by using the arc to chord deviation algorithm or to process the data subsequently.A improved PSO-based improved ICP registration method has been studied to register the data between the scanned point cloud and the original model point cloud. By using the registration method, the high requirement of initial position in ICP can be reduced; the rotation and translation parameters and the cut depth in each machining point can be obtained easily.The development method of the control system was researched. The human interfaces of propeller and data process has been completed by using Visual Basic and Visual C++6.0 in Siemens HMI-Environment. The validity and feasibility of NC system development were verified by real machining experiment on marine propeller.