| The impeller and the blade has complicated thin-walled surface. Normally the blade is processed by five axis NC machine tool. However, during the blade machining, the elastic deformation of the tool and blade will cause errors, which will reduce the machining accuracy of the blade and affect the performance of the impeller. The On Machine Measurement technology could measure the blade machining errors without removing the impeller blank, hence avoiding the fixing errors in the impeller measurement. The thesis apply the On Machine Measurement technology to blade machining, and the machining error compensation method during the blade machining process is studied. The main work is as follows:The blade discrete points is used to model the impeller based on the non-uniform B-spline. The cutter path is planned for the impeller semi-finishing and finishing, and cutter location points and cutter axis vector during the process of impeller machining are obtained.The errors for the On Machine Verification system is calibrated. The error model for five-axis machine tool is established. The laser interferometer and the ball bar is used to get parameters of the machine tool geometric error model. Standard ball is used to calibrate anisotropy and pre-travel error of the probe, and the blade measuring path that matches the cutter location points is generated.The post-process for the five axis NC machine tool is programmed. The Vericut software is used to simulate the machining process. Then the semi finish machining experiment is carried out, and semi finishing machining error data is obtained with On-machine measurement system.Based on the data of semi-finishing machining experiments, the finishing machining error is estimated by the semi-finishing various parameters. Mirror systematic method is used to modify the errors. Lastly, the impeller finishing machining compensation experiment is conducted and the compensation results are analyzed. |
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