Abstract: For the finish milling of the free-form centrifugal impeller channels, based on the comparison between the ball-end milling cutter and the flat-end milling cutter, an optimizing algorithm of the channel finish milling by flat-end milling cutter is proposed to improve the surface finish milling quality and efficiency. An algorithm of the cutter axis vector based on the normal vectors of the impeller channel is deduced by combining the inclination angle and the tilt angle. Compared to the ball-end mill, a model of the flat end milling effective contour is built, the ellipse formula of the contour and the calculation equation of the tool path interval obtained by the flat end milling are deduced. By combining the advantages of the isoparametric method and the constant scallop-height method, a similar triangle calculation of the tool path generation is presented, and, the detailed machining processes of the channel finish milling by the flat-end milling cutter is introduced. The high efficiency of the optimizing algorithm is validated by the cutting simulation and the analysis of the process parameters. The numerical control program and the machining of a real centrifugal compressor impeller are provided to verify the feasibility of the proposed optimizing algorithm.

Key words: Ball-end mill, Bottom of channel, Centrifugal impeller, Flat-end mill, Tool path interval