Iso-parametric path-planning method of twin-tool milling for turbine blades

Twin-tool milling is a new method for turbine blade machining. The dorsal and basin surfaces are machined simultaneously, which can improve the machining efficiency obviously. However, its tool path planning becomes a major challenge due to the asymmetry of the blade surfaces and the structural constraints of the twin-tool machine. In this paper, an iso-parametric path-planning method is proposed for turbine blades milling with twin tools. Considering the structural constraints, the twin-tool orientations are characterized uniformly. In order to guarantee the smoothness of the tool paths, the calculating and equally parameterized fitting algorithm for the cutter contact (CC) points in each path is proposed. Furthermore, the opposite tool paths are matched with a self-defined ratio to realize the simultaneous milling for both blade surfaces. Finally, the tool paths are planned for a typical turbine blade based on the method. The results of simulation and verification experiments show that both blade surfaces are entirely machined. The contour errors can meet the tolerance requirements. In addition, the efficiency increases by about 45% compared with the single-tool milling of the equivalent cutting parameters.