| In this thesis, the geometric modeling and Numerical Control (NC) machining of shrouded impeller, which incorporates a full front and back shroud, are analysed and studied. The researching works include non-uniform B-Spline surface modeling of shrouded impeller, tool selection, nc tool path generation for the channel of shrouded impeller, post-processing, and the simulation in VERICUT. The main works are as follows:1. Build the shrouded impeller model using the algorithms of non-uniform B-spline surface, and merging method of blade edge is given. Embedding MATLAB7.0 environment, the shrouded impeller can be demonstrated.2. Referring to the 5-axis numerical control rough machining of shrouded impeller, a new machining method based on plunge milling was proposed. Plunge milling is low vibration, long hanging and used for superalloy machining, so it's very suitable for rough machining of shrouded impeller3. Rough machining process plan for shrouded impeller is proposed. A reasonable method for channel machining region dividing, which also can be used for machinability evaluation, is put forward. Drilling is another important step in the process. Optimization methods for determination of drilling position and radius are given.4. In this thesis, a NC tool path generation for the channel algorithm of shrouded impeller is proposed. Process is as follows: Firstly, draw gradual change surfaces between the center hole and the impeller channel boundary. Then the impeller channel is machined layer-by-layer along these surfaces. This method can avoid redundancy tool path and improve processing efficiency. Calculation of tool-axis vector was on the basis of interference-free cylindrical region formed by the fabrication hole, thus can effectively avoid frequent calculation of surfaces during interference analysis.5. Post-processing for dual table 5-axis NC machine is given. Carry on the NC machining simulation in VERICUT for the method of tool path generation. The method has been proved available.
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