A combined approach to tool path generation for flank milling of impeller blades with non-developable ruled surfaces

Abstract

Impeller blades are often constructed by non–developable ruled surfaces. Due to their twisted feature, the application of flank milling to these blades would inevitably cause significant interference between the cutter edge and the machined surfaces. In view of the advantages of flank milling operations, this paper proposes a combined approach to flank milling these blade surfaces with acceptable precision and fairly high efficiency. Centring on the minimisation of the interference, the non–developable blade surface is divided into a number of strips, the cutter profile is modified accordingly, and then the tool paths are calculated strip by strip. Along with the basic idea, related issues are investigated in detail focusing on the strip width determination, cutter profile modification, and cutter location calculation. For practical use of the proposed approach, necessary algorithms are also provided. Finally, a case study is presented, together with numerical simulation of the cutting process. The results show that the proposed approach is not only feasible but also much more efficient than the conventional point milling method. [Received 6 November 2013; Revised 16 June 2014; Accepted 2 October 2014]