Study On 4-axis NC Machining Technology For Axial-flow Blade

With the development of CAD/CAM technology and the demand of product performance, the product has more complex shape and requires higher precision. The traditional 3-axis manufacture is unable to product blade that meets the requirement of design. Multi-axis numerical control (NC) machine tools should be applied. In actual manufacture, the 5-axis NC machine tools are expensive and cost much. Applying 4-axis NC machine tools have vantage in efficiency and cost.In this dissertation, the geometry modeling and NC machining technology for blade surface of axial-flow impeller is studied deeply and systematically. The main research consists of non-uniform B-spline modeling method, tool-path generation method of 4-axis NC machining for blade surface, the analysis and fix on interference for cutter axis vector applied in 4-axis NC machining. The main contents are described as follows:1. Build the blades' model using the algorithms of non-uniform B-spline surface. Embedding Matlab7.0 environment, the axial-flow impeller can be demonstrated.2. On the basis of analysis for the tool-path generation method of multi-axis NC machining, iso-parametric method is adopted to generate the machining tool path interval for the blade surface. The tool paths are generated according to one method that based on iso-scallop method. This makes tool-path organized in machining process with no fluctuation. Cutter movement in tool-path meets demanding precision with less step, leads to a higher machining efficiency.3. Methods based on minimum distance method and projection method is adopted to analysis and fix the interference of the cutter axis vector. The vectors of cutter axis are generated by cutter location data, tangent vector and normal vector. The vectors generated are compared to the offset surface of blades to analysis and fix interference, generating new cutter axis vectors that have no interference with surface of blade. The properties of 4-axis post-processing are also analyzed in the dissertation. Different 4-axis post-processing algorithms are involved considering the different configuration of NC machine tools.4 based on the NC program which is generated through post-processing, an experiment is implemented on 4-axis machine tool. The results indicate that the proposed algorithms are correct.